diff --git a/cmd/crossplane/render/engine_docker.go b/cmd/crossplane/render/engine_docker.go
index 9beb3e8c..af5ed8fc 100644
--- a/cmd/crossplane/render/engine_docker.go
+++ b/cmd/crossplane/render/engine_docker.go
@@ -21,6 +21,7 @@ import (
 	"os"
 	"runtime"
 	"strings"
+	"time"
 
 	"google.golang.org/protobuf/proto"
 
@@ -48,6 +49,10 @@ func (realContainerRunner) Run(ctx context.Context, img string, opts ...docker.R
 	return docker.RunContainer(ctx, img, opts...)
 }
 
+// networkRemoveTimeout bounds how long Setup's cleanup waits to remove the
+// temporary render network.
+const networkRemoveTimeout = 30 * time.Second
+
 // dockerRenderEngine executes crossplane internal render in a Docker container.
 type dockerRenderEngine struct {
 	// image is the Crossplane Docker image reference.
@@ -63,6 +68,13 @@ type dockerRenderEngine struct {
 	// (exit-3 partial output, *docker.ContainerExitError vs non-exit errors)
 	// without a real Docker daemon.
 	runner containerRunner
+
+	// networks creates and removes the temporary Docker network Setup owns.
+	// Production callers leave it nil and Setup builds a real client from the
+	// environment only when it needs to create a network. Tests substitute a
+	// fake to exercise the create-network branch without a real Docker
+	// daemon.
+	networks networkClient
 }
 
 func (e *dockerRenderEngine) CheckContextSupport() error {
@@ -95,7 +107,16 @@ func (e *dockerRenderEngine) Setup(ctx context.Context, fns []pkgv1.Function) (f
 		return func() {}, nil
 	}
 
-	networkID, networkName, err := createRenderNetwork(ctx)
+	cli := e.networks
+	if cli == nil {
+		c, err := newNetworkClient()
+		if err != nil {
+			return func() {}, errors.Wrap(err, "cannot create Docker network for rendering")
+		}
+		cli = c
+	}
+
+	networkID, networkName, err := createRenderNetwork(ctx, cli)
 	if err != nil {
 		return func() {}, errors.Wrap(err, "cannot create Docker network for rendering")
 	}
@@ -103,8 +124,17 @@ func (e *dockerRenderEngine) Setup(ctx context.Context, fns []pkgv1.Function) (f
 
 	injectNetworkAnnotation(fns, networkName)
 
-	cleanup := func() { //nolint:contextcheck // Detached context for cleanup.
-		_ = removeRenderNetwork(context.Background(), networkID)
+	cleanup := func() {
+		// Derive from ctx without its cancellation: cleanup typically runs after
+		// the caller's context is done, but must still be bounded so removal
+		// can't hang forever.
+		rctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), networkRemoveTimeout)
+		defer cancel()
+		if err := removeRenderNetwork(rctx, cli, networkID); err != nil {
+			// The cleanup signature can't return the error, so log it rather than
+			// silently leaking the network (e.g. a container is still attached).
+			e.log.Info("Cannot remove Docker network used for rendering", "network", networkName, "id", networkID, "error", err)
+		}
 	}
 
 	return cleanup, nil
diff --git a/cmd/crossplane/render/engine_docker_test.go b/cmd/crossplane/render/engine_docker_test.go
index 73fcdddb..970a7a21 100644
--- a/cmd/crossplane/render/engine_docker_test.go
+++ b/cmd/crossplane/render/engine_docker_test.go
@@ -23,10 +23,13 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+	"github.com/moby/moby/client"
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/testing/protocmp"
 	"google.golang.org/protobuf/types/known/structpb"
 
+	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
 	"github.com/crossplane/crossplane-runtime/v2/pkg/logging"
 
 	pkgv1 "github.com/crossplane/crossplane/apis/v2/pkg/v1"
@@ -222,9 +225,8 @@ func TestDockerRenderEngineSetup(t *testing.T) {
 	// call on the same engine stored its created network there. The branch
 	// must annotate the supplied functions so their containers join the
 	// network, never create a second network, and always return a no-op
-	// cleanup. The create-new-network branch is not covered here because it
-	// depends on a live Docker daemon; the broader render command tests
-	// exercise it integration-style.
+	// cleanup. The create-new-network branch is covered separately by
+	// TestDockerRenderEngineSetupCreatesNetwork.
 	//
 	// The MultiBatchAnnotatesAdditionalFunctions case simulates the
 	// in-process multi-composition use case from crossplane/cli#96: a
@@ -346,6 +348,170 @@ func TestDockerRenderEngineSetup(t *testing.T) {
 	}
 }
 
+func TestDockerRenderEngineSetupCreatesNetwork(t *testing.T) {
+	// When e.network is unset, Setup must create a temporary network through
+	// the engine's network client, record its name, annotate the supplied
+	// functions to join it, and return a cleanup that removes it through the
+	// same client.
+	errBoom := errors.New("boom")
+
+	type args struct {
+		create func(ctx context.Context, name string, options client.NetworkCreateOptions) (client.NetworkCreateResult, error)
+		// removeErr is what NetworkRemove returns. When nil, NetworkRemove
+		// returns the error of the context it is called with, so cleanup
+		// logs an error if it removes the network with a cancelled context.
+		removeErr error
+		// cancel cancels Setup's context before calling cleanup.
+		cancel bool
+	}
+	type want struct {
+		err error
+		// created is whether Setup should create a network, annotate the
+		// functions to join it, and return a cleanup that removes it.
+		created bool
+		// logErr is the error cleanup should log when it cannot remove the
+		// network. When nil, cleanup must log nothing.
+		logErr error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"CreatesNetwork": {
+			reason: "Setup should create a network, annotate the functions to join it, and return a cleanup that removes it.",
+			args: args{
+				create: createRenderNetworkReturns("network-id", nil),
+			},
+			want: want{
+				created: true,
+			},
+		},
+		"CleanupLogsRemoveError": {
+			reason: "The cleanup can't return an error, so it should log a failure to remove the network, with the network's name and ID, rather than discard it.",
+			args: args{
+				create:    createRenderNetworkReturns("network-id", nil),
+				removeErr: errBoom,
+			},
+			want: want{
+				created: true,
+				logErr:  errBoom,
+			},
+		},
+		"CleanupSurvivesCancelledContext": {
+			reason: "The cleanup typically runs after Setup's context is done, so it should still remove the network with a live context.",
+			args: args{
+				create: createRenderNetworkReturns("network-id", nil),
+				cancel: true,
+			},
+			want: want{
+				created: true,
+			},
+		},
+		"NetworkCreateError": {
+			reason: "Setup should return an error and a no-op cleanup, leaving the functions unannotated, when it cannot create the network.",
+			args: args{
+				create: createRenderNetworkReturns("", errBoom),
+			},
+			want: want{
+				err: errBoom,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			// Cleanup discards NetworkRemove's result, so record whether it
+			// was called. A cleanup that shouldn't remove anything leaves
+			// MockNetworkRemove nil.
+			removed := false
+			cli := &mockNetworkClient{MockNetworkCreate: tc.args.create}
+			if tc.want.created {
+				cli.MockNetworkRemove = func(ctx context.Context, networkID string, _ client.NetworkRemoveOptions) (client.NetworkRemoveResult, error) {
+					if diff := cmp.Diff("network-id", networkID); diff != "" {
+						t.Errorf("\n%s\nNetworkRemove(...): -want network ID, +got network ID:\n%s", tc.reason, diff)
+					}
+					removed = true
+					if tc.args.removeErr != nil {
+						return client.NetworkRemoveResult{}, tc.args.removeErr
+					}
+					return client.NetworkRemoveResult{}, ctx.Err()
+				}
+			}
+			log := newRecordingLogger()
+			e := &dockerRenderEngine{log: log, networks: cli}
+			fns := []pkgv1.Function{functionWithAnnotations(nil)}
+
+			ctx, cancel := context.WithCancel(t.Context())
+			defer cancel()
+
+			cleanup, err := e.Setup(ctx, fns)
+
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("\n%s\nSetup(...): -want error, +got error:\n%s", tc.reason, diff)
+			}
+
+			wantFns := []pkgv1.Function{functionWithAnnotations(nil)}
+			if tc.want.created {
+				if !strings.HasPrefix(e.network, renderNetworkPrefix) {
+					t.Errorf("\n%s\nSetup(...): e.network = %q, want a network with prefix %q", tc.reason, e.network, renderNetworkPrefix)
+				}
+				wantFns = []pkgv1.Function{functionWithAnnotations(map[string]string{AnnotationKeyRuntimeDockerNetwork: e.network})}
+			} else if e.network != "" {
+				t.Errorf("\n%s\nSetup(...): e.network = %q, want it unset", tc.reason, e.network)
+			}
+			if diff := cmp.Diff(wantFns, fns); diff != "" {
+				t.Errorf("\n%s\nSetup(...): -want fns, +got fns:\n%s", tc.reason, diff)
+			}
+
+			if tc.args.cancel {
+				cancel()
+			}
+			cleanup()
+
+			if diff := cmp.Diff(tc.want.created, removed); diff != "" {
+				t.Errorf("\n%s\nSetup(...) cleanup: -want network removed, +got network removed:\n%s", tc.reason, diff)
+			}
+			var wantLog []logEntry
+			if tc.want.logErr != nil {
+				wantLog = []logEntry{{
+					Msg: "Cannot remove Docker network used for rendering",
+					KV:  []any{"network", e.network, "id", "network-id", "error", tc.want.logErr},
+				}}
+			}
+			if diff := cmp.Diff(wantLog, *log.entries, cmpopts.EquateErrors(), cmpopts.EquateEmpty()); diff != "" {
+				t.Errorf("\n%s\nSetup(...) cleanup: -want log, +got log:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}
+
+// recordingLogger is a logging.Logger that records every Info and Debug call.
+type recordingLogger struct {
+	entries *[]logEntry
+	kv      []any
+}
+
+type logEntry struct {
+	Msg string
+	KV  []any
+}
+
+var _ logging.Logger = recordingLogger{}
+
+func newRecordingLogger() recordingLogger { return recordingLogger{entries: &[]logEntry{}} }
+
+func (l recordingLogger) Info(msg string, kv ...any) {
+	*l.entries = append(*l.entries, logEntry{Msg: msg, KV: append(append([]any{}, l.kv...), kv...)})
+}
+
+func (l recordingLogger) Debug(msg string, kv ...any) { l.Info(msg, kv...) }
+
+func (l recordingLogger) WithValues(kv ...any) logging.Logger {
+	return recordingLogger{entries: l.entries, kv: append(append([]any{}, l.kv...), kv...)}
+}
+
 // nonExitError is a stand-in for non-*ContainerExitError failures (e.g. image
 // pull errors) returned by docker.RunContainer.
 type nonExitError struct{ msg string }
diff --git a/cmd/crossplane/render/network.go b/cmd/crossplane/render/network.go
index 454b122a..8ef17d68 100644
--- a/cmd/crossplane/render/network.go
+++ b/cmd/crossplane/render/network.go
@@ -46,15 +46,28 @@ func (f *EngineFlags) SetDefaultCrossplaneDockerNetwork(fns []pkgv1.Function) {
 	}
 }
 
-// createRenderNetwork creates a temporary Docker bridge network for render.
-// Function containers and the Crossplane render container join this network so
-// they can reach each other. Returns the network ID and name.
-func createRenderNetwork(ctx context.Context) (string, string, error) {
+// networkClient is the subset of the Docker client the render engine uses to
+// manage its temporary Docker network.
+type networkClient interface {
+	NetworkCreate(ctx context.Context, name string, options client.NetworkCreateOptions) (client.NetworkCreateResult, error)
+	NetworkRemove(ctx context.Context, networkID string, options client.NetworkRemoveOptions) (client.NetworkRemoveResult, error)
+}
+
+var _ networkClient = (*client.Client)(nil)
+
+// newNetworkClient returns a real Docker client built from the environment.
+func newNetworkClient() (networkClient, error) {
 	cli, err := docker.NewClient()
 	if err != nil {
-		return "", "", errors.Wrap(err, "cannot create Docker client")
+		return nil, errors.Wrap(err, "cannot create Docker client")
 	}
+	return cli, nil
+}
 
+// createRenderNetwork creates a temporary Docker bridge network for render.
+// Function containers and the Crossplane render container join this network so
+// they can reach each other. Returns the network ID and name.
+func createRenderNetwork(ctx context.Context, cli networkClient) (string, string, error) {
 	name := fmt.Sprintf("crossplane-render-%s", rand.String(8))
 
 	resp, err := cli.NetworkCreate(ctx, name, client.NetworkCreateOptions{
@@ -68,11 +81,7 @@ func createRenderNetwork(ctx context.Context) (string, string, error) {
 }
 
 // removeRenderNetwork removes a temporary Docker network.
-func removeRenderNetwork(ctx context.Context, networkID string) error {
-	cli, err := docker.NewClient()
-	if err != nil {
-		return errors.Wrap(err, "cannot create Docker client")
-	}
-	_, err = cli.NetworkRemove(ctx, networkID, client.NetworkRemoveOptions{})
+func removeRenderNetwork(ctx context.Context, cli networkClient, networkID string) error {
+	_, err := cli.NetworkRemove(ctx, networkID, client.NetworkRemoveOptions{})
 	return errors.Wrap(err, "cannot remove Docker network")
 }
diff --git a/cmd/crossplane/render/network_test.go b/cmd/crossplane/render/network_test.go
index fde13f0f..843f16f4 100644
--- a/cmd/crossplane/render/network_test.go
+++ b/cmd/crossplane/render/network_test.go
@@ -1,9 +1,15 @@
 package render
 
 import (
+	"context"
+	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+	"github.com/moby/moby/client"
+
+	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
 
 	pkgv1 "github.com/crossplane/crossplane/apis/v2/pkg/v1"
 )
@@ -74,3 +80,152 @@ func TestSetDefaultCrossplaneDockerNetwork(t *testing.T) {
 		})
 	}
 }
+
+type mockNetworkClient struct {
+	MockNetworkCreate func(ctx context.Context, name string, options client.NetworkCreateOptions) (client.NetworkCreateResult, error)
+	MockNetworkRemove func(ctx context.Context, networkID string, options client.NetworkRemoveOptions) (client.NetworkRemoveResult, error)
+}
+
+func (m *mockNetworkClient) NetworkCreate(ctx context.Context, name string, options client.NetworkCreateOptions) (client.NetworkCreateResult, error) {
+	return m.MockNetworkCreate(ctx, name, options)
+}
+
+func (m *mockNetworkClient) NetworkRemove(ctx context.Context, networkID string, options client.NetworkRemoveOptions) (client.NetworkRemoveResult, error) {
+	return m.MockNetworkRemove(ctx, networkID, options)
+}
+
+var _ networkClient = &mockNetworkClient{}
+
+// renderNetworkPrefix is the prefix of the temporary network name
+// createRenderNetwork generates.
+const renderNetworkPrefix = "crossplane-render-"
+
+// createRenderNetworkReturns returns a MockNetworkCreate that returns the
+// supplied network ID and error. It returns an error instead when it is not
+// asked to create a render bridge network.
+func createRenderNetworkReturns(id string, err error) func(context.Context, string, client.NetworkCreateOptions) (client.NetworkCreateResult, error) {
+	return func(_ context.Context, name string, options client.NetworkCreateOptions) (client.NetworkCreateResult, error) {
+		if !strings.HasPrefix(name, renderNetworkPrefix) {
+			return client.NetworkCreateResult{}, errors.Errorf("NetworkCreate(...): name %q does not have prefix %q", name, renderNetworkPrefix)
+		}
+		if diff := cmp.Diff(client.NetworkCreateOptions{Driver: "bridge"}, options); diff != "" {
+			return client.NetworkCreateResult{}, errors.Errorf("NetworkCreate(...): -want options, +got options:\n%s", diff)
+		}
+		return client.NetworkCreateResult{ID: id}, err
+	}
+}
+
+func TestCreateRenderNetwork(t *testing.T) {
+	errBoom := errors.New("boom")
+
+	type args struct {
+		cli networkClient
+	}
+	type want struct {
+		id string
+		// namePrefix is a prefix the returned network name must have. The
+		// rest of the name is random.
+		namePrefix string
+		err        error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"CreatesBridgeNetwork": {
+			reason: "createRenderNetwork should create a uniquely named bridge network through the supplied client and return its ID and name.",
+			args: args{
+				cli: &mockNetworkClient{MockNetworkCreate: createRenderNetworkReturns("network-id", nil)},
+			},
+			want: want{
+				id:         "network-id",
+				namePrefix: renderNetworkPrefix,
+			},
+		},
+		"NetworkCreateError": {
+			reason: "createRenderNetwork should return an error when the client cannot create the network.",
+			args: args{
+				cli: &mockNetworkClient{MockNetworkCreate: createRenderNetworkReturns("", errBoom)},
+			},
+			want: want{
+				err: errBoom,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			id, networkName, err := createRenderNetwork(t.Context(), tc.args.cli)
+
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("\n%s\ncreateRenderNetwork(...): -want error, +got error:\n%s", tc.reason, diff)
+			}
+			if diff := cmp.Diff(tc.want.id, id); diff != "" {
+				t.Errorf("\n%s\ncreateRenderNetwork(...): -want ID, +got ID:\n%s", tc.reason, diff)
+			}
+			if !strings.HasPrefix(networkName, tc.want.namePrefix) {
+				t.Errorf("\n%s\ncreateRenderNetwork(...): name %q does not have prefix %q", tc.reason, networkName, tc.want.namePrefix)
+			}
+		})
+	}
+}
+
+func TestRemoveRenderNetwork(t *testing.T) {
+	errBoom := errors.New("boom")
+
+	// removeNetworkReturns returns a MockNetworkRemove that returns the
+	// supplied error, or an error of its own when asked to remove any network
+	// other than network-id.
+	removeNetworkReturns := func(err error) func(context.Context, string, client.NetworkRemoveOptions) (client.NetworkRemoveResult, error) {
+		return func(_ context.Context, networkID string, _ client.NetworkRemoveOptions) (client.NetworkRemoveResult, error) {
+			if diff := cmp.Diff("network-id", networkID); diff != "" {
+				return client.NetworkRemoveResult{}, errors.Errorf("NetworkRemove(...): -want network ID, +got network ID:\n%s", diff)
+			}
+			return client.NetworkRemoveResult{}, err
+		}
+	}
+
+	type args struct {
+		cli       networkClient
+		networkID string
+	}
+	type want struct {
+		err error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"RemovesNetwork": {
+			reason: "removeRenderNetwork should remove the network with the supplied ID through the supplied client.",
+			args: args{
+				cli:       &mockNetworkClient{MockNetworkRemove: removeNetworkReturns(nil)},
+				networkID: "network-id",
+			},
+		},
+		"NetworkRemoveError": {
+			reason: "removeRenderNetwork should return an error when the client cannot remove the network.",
+			args: args{
+				cli:       &mockNetworkClient{MockNetworkRemove: removeNetworkReturns(errBoom)},
+				networkID: "network-id",
+			},
+			want: want{
+				err: errBoom,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			err := removeRenderNetwork(t.Context(), tc.args.cli, tc.args.networkID)
+
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("\n%s\nremoveRenderNetwork(...): -want error, +got error:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}
diff --git a/cmd/crossplane/render/runtime_docker.go b/cmd/crossplane/render/runtime_docker.go
index 169fe3f5..8972945b 100644
--- a/cmd/crossplane/render/runtime_docker.go
+++ b/cmd/crossplane/render/runtime_docker.go
@@ -161,8 +161,33 @@ type RuntimeDocker struct {
 	// and is reached via host port bindings. When set, the container joins
 	// the specified network and is reached via its Docker hostname on port 9443.
 	Network string
+
+	// dockerClient manages the Function's container. Production callers leave
+	// it nil and Start builds a real client from the environment. Tests
+	// substitute a fake to exercise container lifecycle and cleanup handling
+	// without a real Docker daemon.
+	dockerClient containerClient
+}
+
+// containerClient is the subset of the Docker client RuntimeDocker uses to
+// pull images and manage a Function's container.
+type containerClient interface {
+	pullClient
+	containerCleanupClient
+	ContainerInspect(ctx context.Context, containerID string, options client.ContainerInspectOptions) (client.ContainerInspectResult, error)
+	ContainerCreate(ctx context.Context, options client.ContainerCreateOptions) (client.ContainerCreateResult, error)
+	ContainerStart(ctx context.Context, containerID string, options client.ContainerStartOptions) (client.ContainerStartResult, error)
+}
+
+// containerCleanupClient is the subset of the Docker client RuntimeDocker's
+// stop function uses to clean up a Function's container.
+type containerCleanupClient interface {
+	ContainerStop(ctx context.Context, containerID string, options client.ContainerStopOptions) (client.ContainerStopResult, error)
+	ContainerRemove(ctx context.Context, containerID string, options client.ContainerRemoveOptions) (client.ContainerRemoveResult, error)
 }
 
+var _ containerClient = (*client.Client)(nil)
+
 // GetDockerPullPolicy extracts PullPolicy configuration from the supplied
 // Function.
 func GetDockerPullPolicy(fn pkgv1.Function) (DockerPullPolicy, error) {
@@ -250,7 +275,7 @@ func GetRuntimeDocker(fn pkgv1.Function, log logging.Logger) (*RuntimeDocker, er
 
 var _ Runtime = &RuntimeDocker{}
 
-func (r *RuntimeDocker) findContainer(ctx context.Context, cli *client.Client) (string, error) {
+func (r *RuntimeDocker) findContainer(ctx context.Context, cli containerClient) (string, error) {
 	if r.Name == "" {
 		return "", nil
 	}
@@ -266,7 +291,7 @@ func (r *RuntimeDocker) findContainer(ctx context.Context, cli *client.Client) (
 	return inspect.Container.ID, nil
 }
 
-func (r *RuntimeDocker) createContainer(ctx context.Context, cli *client.Client) (string, error) {
+func (r *RuntimeDocker) createContainer(ctx context.Context, cli containerClient) (string, error) {
 	r.log.Debug("Starting Docker container runtime setup", "image", r.Image)
 
 	// Let Docker automatically allocate an available port on the bind address.
@@ -377,7 +402,7 @@ func (r *RuntimeDocker) createContainer(ctx context.Context, cli *client.Client)
 }
 
 // startContainer ensures the container is running and returns its address.
-func (r *RuntimeDocker) startContainer(ctx context.Context, cli *client.Client, containerID string) (string, error) {
+func (r *RuntimeDocker) startContainer(ctx context.Context, cli containerClient, containerID string) (string, error) {
 	// Start the container (idempotent - safe to call on running containers)
 	if _, err := cli.ContainerStart(ctx, containerID, client.ContainerStartOptions{}); err != nil {
 		return "", errors.Wrap(err, "cannot start Docker container")
@@ -457,9 +482,13 @@ func (r *RuntimeDocker) getPullOptions() (client.ImagePullOptions, error) {
 
 // Start a Function as a Docker container.
 func (r *RuntimeDocker) Start(ctx context.Context) (RuntimeContext, error) {
-	cli, err := client.New(client.FromEnv)
-	if err != nil {
-		return RuntimeContext{}, errors.Wrap(err, "cannot create Docker client using environment variables")
+	cli := r.dockerClient
+	if cli == nil {
+		c, err := client.New(client.FromEnv)
+		if err != nil {
+			return RuntimeContext{}, errors.Wrap(err, "cannot create Docker client using environment variables")
+		}
+		cli = c
 	}
 
 	// Try to find an existing container with the supplied container name.
diff --git a/cmd/crossplane/render/runtime_docker_test.go b/cmd/crossplane/render/runtime_docker_test.go
index a05a6079..68c2e90c 100644
--- a/cmd/crossplane/render/runtime_docker_test.go
+++ b/cmd/crossplane/render/runtime_docker_test.go
@@ -18,13 +18,20 @@ package render
 
 import (
 	"context"
+	"io"
+	"net"
+	"strconv"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
+	"github.com/google/go-containerregistry/pkg/authn"
+	"github.com/moby/moby/api/types/container"
+	"github.com/moby/moby/api/types/network"
 	"github.com/moby/moby/client"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
+	"github.com/crossplane/crossplane-runtime/v2/pkg/errors"
 	"github.com/crossplane/crossplane-runtime/v2/pkg/logging"
 
 	pkgv1 "github.com/crossplane/crossplane/apis/v2/pkg/v1"
@@ -40,6 +47,95 @@ func (m *mockPullClient) ImagePull(ctx context.Context, ref string, options clie
 
 var _ pullClient = &mockPullClient{}
 
+type mockContainerClient struct {
+	MockImagePull        func(ctx context.Context, ref string, options client.ImagePullOptions) (client.ImagePullResponse, error)
+	MockContainerInspect func(ctx context.Context, containerID string, options client.ContainerInspectOptions) (client.ContainerInspectResult, error)
+	MockContainerCreate  func(ctx context.Context, options client.ContainerCreateOptions) (client.ContainerCreateResult, error)
+	MockContainerStart   func(ctx context.Context, containerID string, options client.ContainerStartOptions) (client.ContainerStartResult, error)
+	MockContainerStop    func(ctx context.Context, containerID string, options client.ContainerStopOptions) (client.ContainerStopResult, error)
+	MockContainerRemove  func(ctx context.Context, containerID string, options client.ContainerRemoveOptions) (client.ContainerRemoveResult, error)
+}
+
+func (m *mockContainerClient) ImagePull(ctx context.Context, ref string, options client.ImagePullOptions) (client.ImagePullResponse, error) {
+	return m.MockImagePull(ctx, ref, options)
+}
+
+func (m *mockContainerClient) ContainerInspect(ctx context.Context, containerID string, options client.ContainerInspectOptions) (client.ContainerInspectResult, error) {
+	return m.MockContainerInspect(ctx, containerID, options)
+}
+
+func (m *mockContainerClient) ContainerCreate(ctx context.Context, options client.ContainerCreateOptions) (client.ContainerCreateResult, error) {
+	return m.MockContainerCreate(ctx, options)
+}
+
+func (m *mockContainerClient) ContainerStart(ctx context.Context, containerID string, options client.ContainerStartOptions) (client.ContainerStartResult, error) {
+	return m.MockContainerStart(ctx, containerID, options)
+}
+
+func (m *mockContainerClient) ContainerStop(ctx context.Context, containerID string, options client.ContainerStopOptions) (client.ContainerStopResult, error) {
+	return m.MockContainerStop(ctx, containerID, options)
+}
+
+func (m *mockContainerClient) ContainerRemove(ctx context.Context, containerID string, options client.ContainerRemoveOptions) (client.ContainerRemoveResult, error) {
+	return m.MockContainerRemove(ctx, containerID, options)
+}
+
+var _ containerClient = &mockContainerClient{}
+
+// imagePullDone is a MockImagePull that reports an image pull that has
+// already completed.
+func imagePullDone(context.Context, string, client.ImagePullOptions) (client.ImagePullResponse, error) {
+	return pullDoneResponse{}, nil
+}
+
+// pullDoneResponse is an ImagePullResponse whose body is empty. Only the
+// io.ReadCloser methods PullImage uses are implemented; the embedded
+// interface is nil.
+type pullDoneResponse struct {
+	client.ImagePullResponse
+}
+
+func (pullDoneResponse) Read([]byte) (int, error) { return 0, io.EOF }
+
+func (pullDoneResponse) Close() error { return nil }
+
+// createContainerReturns returns a MockContainerCreate that creates a
+// container with the supplied ID.
+func createContainerReturns(id string) func(context.Context, client.ContainerCreateOptions) (client.ContainerCreateResult, error) {
+	return func(context.Context, client.ContainerCreateOptions) (client.ContainerCreateResult, error) {
+		return client.ContainerCreateResult{ID: id}, nil
+	}
+}
+
+// startContainer returns a MockContainerStart that starts the container with
+// the supplied ID, and returns an error for any other container.
+func startContainer(id string) func(context.Context, string, client.ContainerStartOptions) (client.ContainerStartResult, error) {
+	return func(_ context.Context, containerID string, _ client.ContainerStartOptions) (client.ContainerStartResult, error) {
+		if diff := cmp.Diff(id, containerID); diff != "" {
+			return client.ContainerStartResult{}, errors.Errorf("ContainerStart(...): -want container ID, +got container ID:\n%s", diff)
+		}
+		return client.ContainerStartResult{}, nil
+	}
+}
+
+// inspectContainerOnNetwork returns a MockContainerInspect that reports the
+// container with the supplied ID as running with the supplied name, attached
+// to the supplied Docker network. It returns an error for any other container.
+func inspectContainerOnNetwork(id, name, networkName string) func(context.Context, string, client.ContainerInspectOptions) (client.ContainerInspectResult, error) {
+	return func(_ context.Context, containerID string, _ client.ContainerInspectOptions) (client.ContainerInspectResult, error) {
+		if diff := cmp.Diff(id, containerID); diff != "" {
+			return client.ContainerInspectResult{}, errors.Errorf("ContainerInspect(...): -want container ID, +got container ID:\n%s", diff)
+		}
+		return client.ContainerInspectResult{Container: container.InspectResponse{
+			ID:   id,
+			Name: "/" + name,
+			NetworkSettings: &container.NetworkSettings{
+				Networks: map[string]*network.EndpointSettings{networkName: {}},
+			},
+		}}, nil
+	}
+}
+
 func TestGetRuntimeDocker(t *testing.T) {
 	type args struct {
 		fn pkgv1.Function
@@ -246,3 +342,263 @@ func TestGetRuntimeDocker(t *testing.T) {
 		})
 	}
 }
+
+func TestRuntimeDockerStart(t *testing.T) {
+	const (
+		image         = "xpkg.crossplane.io/crossplane-contrib/function-dummy:v0.1.0"
+		containerID   = "container-id"
+		containerName = "fn-container"
+		dockerNetwork = "render-net"
+	)
+
+	errBoom := errors.New("boom")
+
+	type args struct {
+		pullPolicy DockerPullPolicy
+		cli        *mockContainerClient
+	}
+	type want struct {
+		rctx RuntimeContext
+		err  error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"CreatesAndStartsContainer": {
+			reason: "Start should create, start, and inspect the Function's container through the injected client, without pulling an image that is present.",
+			args: args{
+				pullPolicy: AnnotationValueRuntimeDockerPullPolicyIfNotPresent,
+				cli: &mockContainerClient{
+					MockContainerCreate:  createContainerReturns(containerID),
+					MockContainerStart:   startContainer(containerID),
+					MockContainerInspect: inspectContainerOnNetwork(containerID, containerName, dockerNetwork),
+				},
+			},
+			want: want{
+				rctx: RuntimeContext{Target: net.JoinHostPort(containerName, strconv.Itoa(FunctionPort))},
+			},
+		},
+		"PullsImage": {
+			reason: "Start should pull the Function's image through the injected client when the pull policy is Always.",
+			args: args{
+				pullPolicy: AnnotationValueRuntimeDockerPullPolicyAlways,
+				cli: &mockContainerClient{
+					MockImagePull: func(ctx context.Context, ref string, options client.ImagePullOptions) (client.ImagePullResponse, error) {
+						if diff := cmp.Diff(image, ref); diff != "" {
+							return nil, errors.Errorf("ImagePull(...): -want ref, +got ref:\n%s", diff)
+						}
+						return imagePullDone(ctx, ref, options)
+					},
+					MockContainerCreate:  createContainerReturns(containerID),
+					MockContainerStart:   startContainer(containerID),
+					MockContainerInspect: inspectContainerOnNetwork(containerID, containerName, dockerNetwork),
+				},
+			},
+			want: want{
+				rctx: RuntimeContext{Target: net.JoinHostPort(containerName, strconv.Itoa(FunctionPort))},
+			},
+		},
+		"PullError": {
+			reason: "Start should return an error, without creating a container, when the injected client cannot pull the image.",
+			args: args{
+				pullPolicy: AnnotationValueRuntimeDockerPullPolicyAlways,
+				cli: &mockContainerClient{
+					MockImagePull: func(context.Context, string, client.ImagePullOptions) (client.ImagePullResponse, error) {
+						return nil, errBoom
+					},
+				},
+			},
+			want: want{
+				err: errBoom,
+			},
+		},
+		"StartError": {
+			reason: "Start should return an error when the injected client cannot start the container.",
+			args: args{
+				pullPolicy: AnnotationValueRuntimeDockerPullPolicyIfNotPresent,
+				cli: &mockContainerClient{
+					MockContainerCreate: createContainerReturns(containerID),
+					MockContainerStart: func(context.Context, string, client.ContainerStartOptions) (client.ContainerStartResult, error) {
+						return client.ContainerStartResult{}, errBoom
+					},
+				},
+			},
+			want: want{
+				err: errBoom,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			r := &RuntimeDocker{
+				Image:        image,
+				Cleanup:      AnnotationValueRuntimeDockerCleanupRemove,
+				PullPolicy:   tc.args.pullPolicy,
+				Keychain:     authn.NewMultiKeychain(),
+				Network:      dockerNetwork,
+				log:          logging.NewNopLogger(),
+				dockerClient: tc.args.cli,
+			}
+
+			rctx, err := r.Start(t.Context())
+
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("\n%s\nStart(...): -want error, +got error:\n%s", tc.reason, diff)
+			}
+			if diff := cmp.Diff(tc.want.rctx, rctx, cmpopts.IgnoreFields(RuntimeContext{}, "Stop")); diff != "" {
+				t.Errorf("\n%s\nStart(...): -want, +got:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}
+
+func TestRuntimeDockerStop(t *testing.T) {
+	const (
+		containerID   = "container-id"
+		containerName = "fn-container"
+		dockerNetwork = "render-net"
+	)
+
+	errStop := errors.New("stop boom")
+	errRemove := errors.New("remove boom")
+
+	type args struct {
+		cleanup DockerCleanup
+		// stop and remove are the cleanup client's ContainerStop and
+		// ContainerRemove. A nil mock must not be called. The test checks
+		// the arguments each non-nil mock is called with.
+		stop   func(ctx context.Context, containerID string, options client.ContainerStopOptions) (client.ContainerStopResult, error)
+		remove func(ctx context.Context, containerID string, options client.ContainerRemoveOptions) (client.ContainerRemoveResult, error)
+	}
+	type want struct {
+		err error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"Stop": {
+			reason: "The Stop cleanup policy should stop the container and leave it in place.",
+			args: args{
+				cleanup: AnnotationValueRuntimeDockerCleanupStop,
+				stop: func(context.Context, string, client.ContainerStopOptions) (client.ContainerStopResult, error) {
+					return client.ContainerStopResult{}, nil
+				},
+			},
+		},
+		"StopError": {
+			reason: "The Stop cleanup policy should return an error when the container cannot be stopped.",
+			args: args{
+				cleanup: AnnotationValueRuntimeDockerCleanupStop,
+				stop: func(context.Context, string, client.ContainerStopOptions) (client.ContainerStopResult, error) {
+					return client.ContainerStopResult{}, errStop
+				},
+			},
+			want: want{
+				err: errStop,
+			},
+		},
+		"Remove": {
+			reason: "The Remove cleanup policy should stop the container, then remove it.",
+			args: args{
+				cleanup: AnnotationValueRuntimeDockerCleanupRemove,
+				stop: func(context.Context, string, client.ContainerStopOptions) (client.ContainerStopResult, error) {
+					return client.ContainerStopResult{}, nil
+				},
+				remove: func(context.Context, string, client.ContainerRemoveOptions) (client.ContainerRemoveResult, error) {
+					return client.ContainerRemoveResult{}, nil
+				},
+			},
+		},
+		"RemoveStopError": {
+			reason: "The Remove cleanup policy should stop the container before removing it, and return an error without removing it when it cannot be stopped.",
+			args: args{
+				cleanup: AnnotationValueRuntimeDockerCleanupRemove,
+				stop: func(context.Context, string, client.ContainerStopOptions) (client.ContainerStopResult, error) {
+					return client.ContainerStopResult{}, errStop
+				},
+			},
+			want: want{
+				err: errStop,
+			},
+		},
+		"RemoveError": {
+			reason: "The Remove cleanup policy should return an error when the container cannot be removed.",
+			args: args{
+				cleanup: AnnotationValueRuntimeDockerCleanupRemove,
+				stop: func(context.Context, string, client.ContainerStopOptions) (client.ContainerStopResult, error) {
+					return client.ContainerStopResult{}, nil
+				},
+				remove: func(context.Context, string, client.ContainerRemoveOptions) (client.ContainerRemoveResult, error) {
+					return client.ContainerRemoveResult{}, errRemove
+				},
+			},
+			want: want{
+				err: errRemove,
+			},
+		},
+		"Orphan": {
+			reason: "The Orphan cleanup policy should leave the container running without calling Docker.",
+			args: args{
+				cleanup: AnnotationValueRuntimeDockerCleanupOrphan,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			cli := &mockContainerClient{
+				MockContainerCreate:  createContainerReturns(containerID),
+				MockContainerStart:   startContainer(containerID),
+				MockContainerInspect: inspectContainerOnNetwork(containerID, containerName, dockerNetwork),
+			}
+			if stop := tc.args.stop; stop != nil {
+				cli.MockContainerStop = func(ctx context.Context, id string, options client.ContainerStopOptions) (client.ContainerStopResult, error) {
+					if diff := cmp.Diff(containerID, id); diff != "" {
+						t.Errorf("\n%s\nContainerStop(...): -want container ID, +got container ID:\n%s", tc.reason, diff)
+					}
+					if diff := cmp.Diff(client.ContainerStopOptions{}, options); diff != "" {
+						t.Errorf("\n%s\nContainerStop(...): -want options, +got options:\n%s", tc.reason, diff)
+					}
+					return stop(ctx, id, options)
+				}
+			}
+			if remove := tc.args.remove; remove != nil {
+				cli.MockContainerRemove = func(ctx context.Context, id string, options client.ContainerRemoveOptions) (client.ContainerRemoveResult, error) {
+					if diff := cmp.Diff(containerID, id); diff != "" {
+						t.Errorf("\n%s\nContainerRemove(...): -want container ID, +got container ID:\n%s", tc.reason, diff)
+					}
+					if diff := cmp.Diff(client.ContainerRemoveOptions{}, options); diff != "" {
+						t.Errorf("\n%s\nContainerRemove(...): -want options, +got options:\n%s", tc.reason, diff)
+					}
+					return remove(ctx, id, options)
+				}
+			}
+			r := &RuntimeDocker{
+				Image:        "xpkg.crossplane.io/crossplane-contrib/function-dummy:v0.1.0",
+				Cleanup:      tc.args.cleanup,
+				PullPolicy:   AnnotationValueRuntimeDockerPullPolicyIfNotPresent,
+				Keychain:     authn.NewMultiKeychain(),
+				Network:      dockerNetwork,
+				log:          logging.NewNopLogger(),
+				dockerClient: cli,
+			}
+
+			rctx, err := r.Start(t.Context())
+			if err != nil {
+				t.Fatalf("\n%s\nStart(...): unexpected error: %v", tc.reason, err)
+			}
+
+			err = rctx.Stop(t.Context())
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("\n%s\nStop(...): -want error, +got error:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}