diff --git a/.github/workflows/dev.yml b/.github/workflows/dev.yml
index 7c3607bd1df3..9419f2f2029e 100644
--- a/.github/workflows/dev.yml
+++ b/.github/workflows/dev.yml
@@ -39,6 +39,20 @@ env:
 
 jobs:
 
+  pr-scripts:
+    name: PR Workflow Script Tests
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v7
+        with:
+          persist-credentials: false
+      - uses: actions/setup-node@v6
+        with:
+          node-version: '24'
+      - name: Test PR workflow scripts
+        run: node --test .github/workflows/dev_pr/*.test.js
+
   lint:
     name: Lint C++, Python, R, Docker, RAT
     # Use Ubuntu 24.04 to ensure working pre-commit on Ubuntu 24.04.
diff --git a/.github/workflows/dev_pr/issue_check.js b/.github/workflows/dev_pr/issue_check.js
index 176349cdd051..ef2187af504d 100644
--- a/.github/workflows/dev_pr/issue_check.js
+++ b/.github/workflows/dev_pr/issue_check.js
@@ -26,17 +26,24 @@ const helpers = require("./helpers.js");
  * @param {Object} issueInfo
  */
 async function assignGitHubIssue(github, context, pullRequestNumber, issueInfo) {
-    await github.rest.issues.addAssignees({
+    const creator = context.payload.pull_request.user.login;
+    const response = await github.rest.issues.addAssignees({
         owner: context.repo.owner,
         repo: context.repo.repo,
         issue_number: issueInfo.number,
-        assignees: context.payload.pull_request.user.login
+        assignees: [creator]
     });
+    const assigned = response.data.assignees.some((assignee) => assignee.login === creator);
+    const body = assigned
+        ? ":warning: GitHub issue #" + issueInfo.number + " **has been automatically assigned in GitHub** to PR creator."
+        : ":warning: GitHub issue #" + issueInfo.number + " **could not be automatically assigned** to the PR creator. " +
+          "Please leave a comment on " + issueInfo.html_url + " requesting assignment. " +
+          "A committer or collaborator can then assign the issue to you.";
     await github.rest.issues.createComment({
         owner: context.repo.owner,
         repo: context.repo.repo,
         issue_number: pullRequestNumber,
-        body: ":warning: GitHub issue #" + issueInfo.number + " **has been automatically assigned in GitHub** to PR creator."
+        body
     });
 }
 
diff --git a/.github/workflows/dev_pr/issue_check.test.js b/.github/workflows/dev_pr/issue_check.test.js
new file mode 100644
index 000000000000..37a50e7c9b9e
--- /dev/null
+++ b/.github/workflows/dev_pr/issue_check.test.js
@@ -0,0 +1,102 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+const assert = require("node:assert/strict");
+const {test, mock} = require("node:test");
+const checkIssue = require("./issue_check.js");
+
+function request({assignees = [], returnedAssignees = [{login: "contributor"}],
+                  title = "GH-34389: Check assignment results"} = {}) {
+    const issue = {
+        number: 34389,
+        html_url: "https://github.com/apache/arrow/issues/34389",
+        assignees,
+        labels: [{name: "Component: Developer Tools"}]
+    };
+    const issues = {
+        get: mock.fn(async () => ({data: issue})),
+        addAssignees: mock.fn(async () => ({
+            data: {...issue, assignees: returnedAssignees}
+        })),
+        createComment: mock.fn(async () => ({}))
+    };
+    const github = {rest: {issues}};
+    const context = {
+        repo: {owner: "apache", repo: "arrow"},
+        payload: {
+            number: 50000,
+            pull_request: {title, user: {login: "contributor"}}
+        }
+    };
+    return {github, context, issues};
+}
+
+test("reports successful assignment only after GitHub assigns the PR creator", async () => {
+    const input = request();
+    await checkIssue(input);
+
+    assert.equal(input.issues.addAssignees.mock.callCount(), 1);
+    assert.deepEqual(input.issues.addAssignees.mock.calls[0].arguments[0], {
+        owner: "apache", repo: "arrow", issue_number: 34389,
+        assignees: ["contributor"]
+    });
+    assert.equal(input.issues.createComment.mock.callCount(), 1);
+    assert.deepEqual(input.issues.createComment.mock.calls[0].arguments[0], {
+        owner: "apache", repo: "arrow", issue_number: 50000,
+        body: ":warning: GitHub issue #34389 **has been automatically assigned in GitHub** to PR creator."
+    });
+});
+
+for (const [description, returnedAssignees] of [
+    ["silently ignores the assignment", []],
+    ["returns a different assignee", [{login: "another-contributor"}]]
+]) {
+    test(`provides assignment instructions when GitHub ${description}`, async () => {
+        const input = request({returnedAssignees});
+        await checkIssue(input);
+
+        assert.equal(input.issues.addAssignees.mock.callCount(), 1);
+        assert.equal(input.issues.createComment.mock.callCount(), 1);
+        const comment = input.issues.createComment.mock.calls[0].arguments[0];
+        assert.equal(comment.issue_number, 50000);
+        assert.doesNotMatch(comment.body, /has been automatically assigned/);
+        assert.match(comment.body, /https:\/\/github.com\/apache\/arrow\/issues\/34389/);
+        assert.match(comment.body, /comment/i);
+        assert.match(comment.body, /assign/i);
+        assert.match(comment.body, /maintainer|committer|collaborator/i);
+    });
+}
+
+test("leaves an already assigned issue unchanged", async () => {
+    const input = request({assignees: [{login: "another-contributor"}]});
+    await checkIssue(input);
+
+    assert.equal(input.issues.get.mock.callCount(), 1);
+    assert.equal(input.issues.addAssignees.mock.callCount(), 0);
+    assert.equal(input.issues.createComment.mock.callCount(), 0);
+});
+
+for (const title of ["MINOR: Fix a typo", "Fix assignment results"]) {
+    test(`skips API calls for PR title '${title}'`, async () => {
+        const input = request({title});
+        await checkIssue(input);
+
+        assert.equal(input.issues.get.mock.callCount(), 0);
+        assert.equal(input.issues.addAssignees.mock.callCount(), 0);
+        assert.equal(input.issues.createComment.mock.callCount(), 0);
+    });
+}