diff --git a/experimental/CHANGELOG.md b/experimental/CHANGELOG.md
index c5d948a14f2..ccee66cc8a8 100644
--- a/experimental/CHANGELOG.md
+++ b/experimental/CHANGELOG.md
@@ -14,6 +14,7 @@ For notes on migrating to 2.x / 0.200.x see [the upgrade guide](doc/upgrade-to-2
 
 * fix(sdk-logs): allow AnyValue attributes for logs and handle circular references [#6210](https://github.com/open-telemetry/opentelemetry-js/pull/6210) @david-luna
   * based on [#5765](https://github.com/open-telemetry/opentelemetry-js/pull/5765) from @alec2435
+* fix(browser-detector): use window feature detection to avoid false positives in Node.js 21+ and Bun [#6271](https://github.com/open-telemetry/opentelemetry-js/pull/6271) @fiyinfoluwa001 @overbalance
 
 ### :books: Documentation
 
diff --git a/experimental/packages/opentelemetry-browser-detector/src/BrowserDetector.ts b/experimental/packages/opentelemetry-browser-detector/src/BrowserDetector.ts
index 3cfc05ca80d..2c482901a80 100644
--- a/experimental/packages/opentelemetry-browser-detector/src/BrowserDetector.ts
+++ b/experimental/packages/opentelemetry-browser-detector/src/BrowserDetector.ts
@@ -28,7 +28,9 @@ import { BROWSER_ATTRIBUTES, UserAgentData } from './types';
  */
 class BrowserDetector implements ResourceDetector {
   detect(config?: ResourceDetectionConfig): DetectedResource {
-    const isBrowser = typeof navigator !== 'undefined';
+    const isBrowser =
+      typeof window !== 'undefined' && typeof document !== 'undefined';
+
     if (!isBrowser) {
       return emptyResource();
     }
diff --git a/experimental/packages/opentelemetry-browser-detector/test/BrowserDetector.test.ts b/experimental/packages/opentelemetry-browser-detector/test/BrowserDetector.test.ts
index 758ca395819..73e1b4ba4f1 100644
--- a/experimental/packages/opentelemetry-browser-detector/test/BrowserDetector.test.ts
+++ b/experimental/packages/opentelemetry-browser-detector/test/BrowserDetector.test.ts
@@ -15,7 +15,12 @@
  */
 import * as sinon from 'sinon';
 import { browserDetector } from '../src/BrowserDetector';
-import { assertEmptyResource, assertResource, describeBrowser } from './util';
+import {
+  assertEmptyResource,
+  assertResource,
+  describeBrowser,
+  describeNode,
+} from './util';
 
 describeBrowser('browserDetector()', () => {
   afterEach(() => {
@@ -69,7 +74,7 @@ describeBrowser('browserDetector()', () => {
     });
   });
 
-  it('should return empty resources if user agent is missing', async () => {
+  it('should return empty resource if userAgent is missing', async () => {
     sinon.stub(globalThis, 'navigator').value({
       userAgent: '',
     });
@@ -77,3 +82,20 @@ describeBrowser('browserDetector()', () => {
     assertEmptyResource(resource);
   });
 });
+
+describeNode('browserDetector()', () => {
+  it('should return empty resource even if navigator is present', () => {
+    // Cannot use sinon.stub for non-existent properties (Node.js <=20)
+    Object.defineProperty(globalThis, 'navigator', {
+      value: {
+        userAgent: 'dddd',
+        language: 'en-US',
+        userAgentData: undefined,
+      },
+      configurable: true,
+    });
+
+    const resource = browserDetector.detect();
+    assertEmptyResource(resource);
+  });
+});
diff --git a/experimental/packages/opentelemetry-browser-detector/test/util.ts b/experimental/packages/opentelemetry-browser-detector/test/util.ts
index c51862adc1c..f5ffdb0ff49 100644
--- a/experimental/packages/opentelemetry-browser-detector/test/util.ts
+++ b/experimental/packages/opentelemetry-browser-detector/test/util.ts
@@ -18,9 +18,20 @@ import * as assert from 'assert';
 import { BROWSER_ATTRIBUTES } from '../src/types';
 import { DetectedResource } from '@opentelemetry/resources';
 
+const isBrowser =
+  typeof window !== 'undefined' && typeof document !== 'undefined';
+
 export function describeBrowser(title: string, fn: (this: Suite) => void) {
   title = `Browser: ${title}`;
-  if (typeof process === 'object' && process.release?.name === 'node') {
+  if (isBrowser) {
+    return describe(title, fn);
+  }
+  return describe.skip(title, fn);
+}
+
+export function describeNode(title: string, fn: (this: Suite) => void) {
+  title = `Node.js: ${title}`;
+  if (isBrowser) {
     return describe.skip(title, fn);
   }
   return describe(title, fn);