diff --git a/packages/browser/src/integrations/fetchStreamPerformance.ts b/packages/browser/src/integrations/fetchStreamPerformance.ts
index c021c959e883..735746fe9ac7 100644
--- a/packages/browser/src/integrations/fetchStreamPerformance.ts
+++ b/packages/browser/src/integrations/fetchStreamPerformance.ts
@@ -81,7 +81,7 @@ export const fetchStreamPerformanceIntegration = defineIntegration(() => {
               : url;
 
           // `http.client.stream` follows the same name rules as `http.client`.
-          const domain = getUrlDomain(url, WINDOW.location?.origin);
+          const domain = getUrlDomain(url, WINDOW.location?.href);
           const streamedName = domain ? `${method} ${domain}` : method;
           const streamSpan = startInactiveSpan({
             name: hasSpanStreamingEnabled(client) ? streamedName : `${method} ${sanitizedUrl}`,
diff --git a/packages/browser/src/tracing/request.ts b/packages/browser/src/tracing/request.ts
index dd5cdb351a3c..31e1b831218e 100644
--- a/packages/browser/src/tracing/request.ts
+++ b/packages/browser/src/tracing/request.ts
@@ -155,7 +155,7 @@ export function instrumentOutgoingRequests(client: Client, _options?: Partial<Re
         propagateTraceparent,
         onRequestSpanEnd,
         // The generic fetch instrumentation has no page origin to resolve relative URLs against.
-        urlBase: WINDOW.location?.origin,
+        urlBase: WINDOW.location?.href,
       });
 
       // We cannot use `window.location` in the generic fetch instrumentation,
@@ -376,7 +376,7 @@ function xhrCallback(
 
   // `parseUrl` returns the raw authority — userinfo credentials must never reach an attribute.
   const host = parsedUrl?.host?.replace(/^.*@/, '');
-  // `getFullURL` already resolved relative URLs against the page origin; only data URLs have no domain.
+  // `getFullURL` already resolved relative URLs against the page URL; only data URLs have no domain.
   const domain = getUrlDomain(fullUrl || url);
 
   // With span streaming, span names have to be low cardinality, so only the domain is kept.
diff --git a/packages/browser/src/tracing/utils.ts b/packages/browser/src/tracing/utils.ts
index c422e3438fd9..de9c3c6a7f55 100644
--- a/packages/browser/src/tracing/utils.ts
+++ b/packages/browser/src/tracing/utils.ts
@@ -14,7 +14,7 @@ export function getFullURL(url: string): string | undefined {
   try {
     // By adding a base URL to new URL(), this will also work for relative urls
     // If `url` is a full URL, the base URL is ignored anyhow
-    const parsed = new URL(url, WINDOW.location.origin);
+    const parsed = new URL(url, WINDOW.location?.href);
     return parsed.href;
   } catch {
     return undefined;
diff --git a/packages/browser/test/integrations/fetchStreamPerformance.test.ts b/packages/browser/test/integrations/fetchStreamPerformance.test.ts
index b74919be9430..dcc5bdc2b86c 100644
--- a/packages/browser/test/integrations/fetchStreamPerformance.test.ts
+++ b/packages/browser/test/integrations/fetchStreamPerformance.test.ts
@@ -1,13 +1,14 @@
 import type { Client, HandlerDataFetch } from '@sentry/core';
 import * as utils from '@sentry/core';
 import * as coreBrowser from '@sentry/core/browser';
+import { URL_DOMAIN } from '@sentry/conventions/attributes';
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { fetchStreamPerformanceIntegration } from '../../src/integrations/fetchStreamPerformance';
 
 describe('fetchStreamPerformanceIntegration', () => {
   beforeEach(() => {
     vi.clearAllMocks();
-    vi.stubGlobal('location', { origin: 'https://app.example.com' });
+    vi.stubGlobal('location', { origin: 'https://app.example.com', href: 'https://app.example.com/' });
   });
 
   afterEach(() => {
@@ -48,16 +49,27 @@ describe('fetchStreamPerformanceIntegration', () => {
     expect(trackStreamedFetch('stream', 'https://api.example.com/v1/chat?stream=1')).toHaveBeenCalledWith(
       expect.objectContaining({
         name: 'GET api.example.com',
-        attributes: expect.objectContaining({ 'url.domain': 'api.example.com' }),
+        attributes: expect.objectContaining({ [URL_DOMAIN]: 'api.example.com' }),
       }),
     );
   });
 
-  it('resolves a relative URL against the page origin', () => {
+  it('resolves a relative URL against the page URL', () => {
     expect(trackStreamedFetch('stream', '/v1/chat')).toHaveBeenCalledWith(
       expect.objectContaining({
         name: 'GET app.example.com',
-        attributes: expect.objectContaining({ 'url.domain': 'app.example.com' }),
+        attributes: expect.objectContaining({ [URL_DOMAIN]: 'app.example.com' }),
+      }),
+    );
+  });
+
+  it('keeps the domain of an absolute URL on a page with an opaque origin', () => {
+    vi.stubGlobal('location', { origin: 'null', href: 'about:srcdoc' });
+
+    expect(trackStreamedFetch('stream', 'https://api.example.com/v1/chat')).toHaveBeenCalledWith(
+      expect.objectContaining({
+        name: 'GET api.example.com',
+        attributes: expect.objectContaining({ [URL_DOMAIN]: 'api.example.com' }),
       }),
     );
   });
@@ -66,7 +78,7 @@ describe('fetchStreamPerformanceIntegration', () => {
     expect(trackStreamedFetch('stream', 'data:text/event-stream,data: hi')).toHaveBeenCalledWith(
       expect.objectContaining({
         name: 'GET',
-        attributes: expect.objectContaining({ 'url.domain': undefined }),
+        attributes: expect.objectContaining({ [URL_DOMAIN]: undefined }),
       }),
     );
   });
@@ -75,7 +87,7 @@ describe('fetchStreamPerformanceIntegration', () => {
     expect(trackStreamedFetch('static', 'https://api.example.com/v1/chat?stream=1')).toHaveBeenCalledWith(
       expect.objectContaining({
         name: 'GET https://api.example.com/v1/chat',
-        attributes: expect.objectContaining({ 'url.domain': 'api.example.com' }),
+        attributes: expect.objectContaining({ [URL_DOMAIN]: 'api.example.com' }),
       }),
     );
   });
diff --git a/packages/browser/test/tracing/request.test.ts b/packages/browser/test/tracing/request.test.ts
index 6db5493e742a..e0c8fe8f0947 100644
--- a/packages/browser/test/tracing/request.test.ts
+++ b/packages/browser/test/tracing/request.test.ts
@@ -2,7 +2,7 @@ import type { Client } from '@sentry/core';
 import * as utils from '@sentry/core';
 import * as coreBrowser from '@sentry/core/browser';
 import * as browserUtils from '@sentry/browser-utils';
-import { HTTP_REQUEST_METHOD } from '@sentry/conventions/attributes';
+import { HTTP_REQUEST_METHOD, SERVER_ADDRESS, URL_DOMAIN, URL_FULL } from '@sentry/conventions/attributes';
 import type { MockInstance } from 'vitest';
 import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest';
 import { BrowserClient } from '../../src/client';
@@ -223,12 +223,12 @@ describe('instrumentOutgoingRequests', () => {
 
     const requestSpanJson = utils.spanToJSON(requestSpan!);
     expect(requestSpanJson.name).toBe('GET example.com');
-    expect(requestSpanJson.attributes['url.domain']).toBe('example.com');
-    expect(requestSpanJson.attributes['server.address']).toBe('example.com:8443');
+    expect(requestSpanJson.attributes[URL_DOMAIN]).toBe('example.com');
+    expect(requestSpanJson.attributes[SERVER_ADDRESS]).toBe('example.com:8443');
   });
 
-  it('resolves a relative fetch URL against the page origin for the streamed span name', () => {
-    vi.stubGlobal('location', { origin: 'https://app.example.com' });
+  it('resolves a relative fetch URL against the page URL for the streamed span name', () => {
+    vi.stubGlobal('location', { origin: 'https://app.example.com', href: 'https://app.example.com/' });
 
     let fetchHandler: ((data: utils.HandlerDataFetch) => void) | undefined;
     let requestSpan: utils.Span | undefined;
@@ -255,13 +255,13 @@ describe('instrumentOutgoingRequests', () => {
 
     const requestSpanJson = utils.spanToJSON(requestSpan!);
     expect(requestSpanJson.name).toBe('GET app.example.com');
-    expect(requestSpanJson.attributes['url.domain']).toBe('app.example.com');
+    expect(requestSpanJson.attributes[URL_DOMAIN]).toBe('app.example.com');
 
     vi.unstubAllGlobals();
   });
 
-  it('resolves a relative XHR URL against the page origin for the streamed span name', () => {
-    vi.stubGlobal('location', { origin: 'https://app.example.com' });
+  it('resolves a relative XHR URL against the page URL for the streamed span name', () => {
+    vi.stubGlobal('location', { origin: 'https://app.example.com', href: 'https://app.example.com/' });
 
     let xhrHandler: ((data: utils.HandlerDataXhr) => void) | undefined;
     let requestSpan: utils.Span | undefined;
@@ -294,11 +294,94 @@ describe('instrumentOutgoingRequests', () => {
 
     const requestSpanJson = utils.spanToJSON(requestSpan!);
     expect(requestSpanJson.name).toBe('GET app.example.com');
-    expect(requestSpanJson.attributes['url.domain']).toBe('app.example.com');
+    expect(requestSpanJson.attributes[URL_DOMAIN]).toBe('app.example.com');
 
     vi.unstubAllGlobals();
   });
 
+  describe('resolving request URLs against location.href', () => {
+    afterEach(() => {
+      vi.unstubAllGlobals();
+    });
+
+    it.each([
+      {
+        name: 'an absolute URL on a page with an opaque origin',
+        location: { origin: 'null', href: 'about:srcdoc' },
+        requestUrl: 'https://api.example.org/v1/users',
+        expected: 'https://api.example.org/v1/users',
+      },
+      {
+        name: 'a relative path without a leading slash',
+        location: { origin: 'https://app.example.com', href: 'https://app.example.com/dashboard/settings' },
+        requestUrl: 'users',
+        expected: 'https://app.example.com/dashboard/users',
+      },
+    ])('sets url.full on XHR spans for $name', ({ location, requestUrl, expected }) => {
+      vi.stubGlobal('location', location);
+
+      let xhrHandler: ((data: utils.HandlerDataXhr) => void) | undefined;
+      let requestSpan: utils.Span | undefined;
+
+      vi.spyOn(browserUtils, 'addXhrInstrumentationHandler').mockImplementation(handler => {
+        xhrHandler = handler;
+      });
+      const tracingClient = new BrowserClient(getDefaultBrowserClientOptions({ tracesSampleRate: 1 }));
+      utils.setCurrentClient(tracingClient);
+      utils._INTERNAL_setSpanForScope(utils.getCurrentScope(), new utils.SentrySpan({ sampled: true }));
+
+      instrumentOutgoingRequests(tracingClient, {
+        traceFetch: false,
+        enableHTTPTimings: false,
+        onRequestSpanStart: span => {
+          requestSpan = span;
+        },
+      });
+      xhrHandler?.({
+        xhr: {
+          [browserUtils.SENTRY_XHR_DATA_KEY]: {
+            method: 'GET',
+            url: requestUrl,
+            request_headers: {},
+          },
+          setRequestHeader: vi.fn(),
+        },
+        startTimestamp: Date.now(),
+      } as utils.HandlerDataXhr);
+
+      expect(utils.spanToJSON(requestSpan!).attributes[URL_FULL]).toBe(expected);
+    });
+
+    it('sets url.domain on fetch spans for an absolute URL on a page with an opaque origin', () => {
+      vi.stubGlobal('location', { origin: 'null', href: 'about:srcdoc' });
+
+      let fetchHandler: ((data: utils.HandlerDataFetch) => void) | undefined;
+      let requestSpan: utils.Span | undefined;
+
+      vi.spyOn(utils, 'addFetchInstrumentationHandler').mockImplementation(handler => {
+        fetchHandler = handler;
+      });
+      const tracingClient = new BrowserClient(getDefaultBrowserClientOptions({ tracesSampleRate: 1 }));
+      utils.setCurrentClient(tracingClient);
+      utils._INTERNAL_setSpanForScope(utils.getCurrentScope(), new utils.SentrySpan({ sampled: true }));
+
+      instrumentOutgoingRequests(tracingClient, {
+        traceXHR: false,
+        enableHTTPTimings: false,
+        onRequestSpanStart: span => {
+          requestSpan = span;
+        },
+      });
+      fetchHandler?.({
+        fetchData: { method: 'GET', url: 'https://api.example.org/v1/users' },
+        args: ['https://api.example.org/v1/users'],
+        startTimestamp: Date.now(),
+      });
+
+      expect(utils.spanToJSON(requestSpan!).attributes[URL_DOMAIN]).toBe('api.example.org');
+    });
+  });
+
   it('falls back to the request method for a data URL, which has no domain', () => {
     let fetchHandler: ((data: utils.HandlerDataFetch) => void) | undefined;
     let requestSpan: utils.Span | undefined;
@@ -325,7 +408,7 @@ describe('instrumentOutgoingRequests', () => {
 
     const requestSpanJson = utils.spanToJSON(requestSpan!);
     expect(requestSpanJson.name).toBe('GET');
-    expect(requestSpanJson.attributes['url.domain']).toBeUndefined();
+    expect(requestSpanJson.attributes[URL_DOMAIN]).toBeUndefined();
   });
 
   describe('XHR trace header span', () => {
diff --git a/packages/core/src/fetch.ts b/packages/core/src/fetch.ts
index 76ef3892bea1..314aeac57e71 100644
--- a/packages/core/src/fetch.ts
+++ b/packages/core/src/fetch.ts
@@ -52,7 +52,7 @@ interface InstrumentFetchRequestOptions {
   spanOrigin?: SpanOrigin;
   propagateTraceparent?: boolean;
   onRequestSpanEnd?: (span: Span, responseInformation: ResponseHookInfo) => void;
-  /** Base URL for relative request URLs. Browsers pass the page origin; server runtimes have none. */
+  /** Base URL for relative request URLs. Browsers pass the page URL; server runtimes have none. */
   urlBase?: string;
 }