diff --git a/packages/playwright-core/src/server/bidi/bidiFirefox.ts b/packages/playwright-core/src/server/bidi/bidiFirefox.ts
index 737fc97eaa..204cabdef7 100644
--- a/packages/playwright-core/src/server/bidi/bidiFirefox.ts
+++ b/packages/playwright-core/src/server/bidi/bidiFirefox.ts
@@ -26,6 +26,7 @@ import type { ConnectionTransport } from '../transport';
 import type * as types from '../types';
 import { BidiBrowser } from './bidiBrowser';
 import { kBrowserCloseMessageId } from './bidiConnection';
+import { createProfile } from './third_party/firefoxPrefs';
 
 export class BidiFirefox extends BrowserType {
   constructor(parent: SdkObject) {
@@ -72,6 +73,13 @@ export class BidiFirefox extends BrowserType {
     transport.send({ method: 'browser.close', params: {}, id: kBrowserCloseMessageId });
   }
 
+  override async prepareUserDataDir(options: types.LaunchOptions, userDataDir: string): Promise<void> {
+    await createProfile({
+      path: userDataDir,
+      preferences: options.firefoxUserPrefs || {},
+    });
+  }
+
   override defaultArgs(options: types.LaunchOptions, isPersistent: boolean, userDataDir: string): string[] {
     const { args = [], headless } = options;
     const userDataDirArg = args.find(arg => arg.startsWith('-profile') || arg.startsWith('--profile'));
diff --git a/packages/playwright-core/src/server/bidi/third_party/firefoxPrefs.ts b/packages/playwright-core/src/server/bidi/third_party/firefoxPrefs.ts
new file mode 100644
index 0000000000..7c08bebe6d
--- /dev/null
+++ b/packages/playwright-core/src/server/bidi/third_party/firefoxPrefs.ts
@@ -0,0 +1,282 @@
+/**
+ * @license
+ * Copyright 2023 Google Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import fs from 'fs';
+import path from 'path';
+
+/* eslint-disable curly, indent */
+
+interface ProfileOptions {
+  preferences: Record<string, unknown>;
+  path: string;
+}
+
+export async function createProfile(options: ProfileOptions): Promise<void> {
+  if (!fs.existsSync(options.path)) {
+    await fs.promises.mkdir(options.path, {
+      recursive: true,
+    });
+  }
+  await writePreferences({
+    preferences: {
+      ...defaultProfilePreferences(options.preferences),
+      ...options.preferences,
+    },
+    path: options.path,
+  });
+}
+
+function defaultProfilePreferences(
+  extraPrefs: Record<string, unknown>
+): Record<string, unknown> {
+  const server = 'dummy.test';
+
+  const defaultPrefs = {
+    // Make sure Shield doesn't hit the network.
+    'app.normandy.api_url': '',
+    // Disable Firefox old build background check
+    'app.update.checkInstallTime': false,
+    // Disable automatically upgrading Firefox
+    'app.update.disabledForTesting': true,
+
+    // Increase the APZ content response timeout to 1 minute
+    'apz.content_response_timeout': 60000,
+
+    // Prevent various error message on the console
+    // jest-puppeteer asserts that no error message is emitted by the console
+    'browser.contentblocking.features.standard':
+      '-tp,tpPrivate,cookieBehavior0,-cm,-fp',
+
+    // Enable the dump function: which sends messages to the system
+    // console
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1543115
+    'browser.dom.window.dump.enabled': true,
+    // Disable topstories
+    'browser.newtabpage.activity-stream.feeds.system.topstories': false,
+    // Always display a blank page
+    'browser.newtabpage.enabled': false,
+    // Background thumbnails in particular cause grief: and disabling
+    // thumbnails in general cannot hurt
+    'browser.pagethumbnails.capturing_disabled': true,
+
+    // Disable safebrowsing components.
+    'browser.safebrowsing.blockedURIs.enabled': false,
+    'browser.safebrowsing.downloads.enabled': false,
+    'browser.safebrowsing.malware.enabled': false,
+    'browser.safebrowsing.phishing.enabled': false,
+
+    // Disable updates to search engines.
+    'browser.search.update': false,
+    // Do not restore the last open set of tabs if the browser has crashed
+    'browser.sessionstore.resume_from_crash': false,
+    // Skip check for default browser on startup
+    'browser.shell.checkDefaultBrowser': false,
+
+    // Disable newtabpage
+    'browser.startup.homepage': 'about:blank',
+    // Do not redirect user when a milstone upgrade of Firefox is detected
+    'browser.startup.homepage_override.mstone': 'ignore',
+    // Start with a blank page about:blank
+    'browser.startup.page': 0,
+
+    // Do not allow background tabs to be zombified on Android: otherwise for
+    // tests that open additional tabs: the test harness tab itself might get
+    // unloaded
+    'browser.tabs.disableBackgroundZombification': false,
+    // Do not warn when closing all other open tabs
+    'browser.tabs.warnOnCloseOtherTabs': false,
+    // Do not warn when multiple tabs will be opened
+    'browser.tabs.warnOnOpen': false,
+
+    // Do not automatically offer translations, as tests do not expect this.
+    'browser.translations.automaticallyPopup': false,
+
+    // Disable the UI tour.
+    'browser.uitour.enabled': false,
+    // Turn off search suggestions in the location bar so as not to trigger
+    // network connections.
+    'browser.urlbar.suggest.searches': false,
+    // Disable first run splash page on Windows 10
+    'browser.usedOnWindows10.introURL': '',
+    // Do not warn on quitting Firefox
+    'browser.warnOnQuit': false,
+
+    // Defensively disable data reporting systems
+    'datareporting.healthreport.documentServerURI': `http://${server}/dummy/healthreport/`,
+    'datareporting.healthreport.logging.consoleEnabled': false,
+    'datareporting.healthreport.service.enabled': false,
+    'datareporting.healthreport.service.firstRun': false,
+    'datareporting.healthreport.uploadEnabled': false,
+
+    // Do not show datareporting policy notifications which can interfere with tests
+    'datareporting.policy.dataSubmissionEnabled': false,
+    'datareporting.policy.dataSubmissionPolicyBypassNotification': true,
+
+    // DevTools JSONViewer sometimes fails to load dependencies with its require.js.
+    // This doesn't affect Puppeteer but spams console (Bug 1424372)
+    'devtools.jsonview.enabled': false,
+
+    // Disable popup-blocker
+    'dom.disable_open_during_load': false,
+
+    // Enable the support for File object creation in the content process
+    // Required for |Page.setFileInputFiles| protocol method.
+    'dom.file.createInChild': true,
+
+    // Disable the ProcessHangMonitor
+    'dom.ipc.reportProcessHangs': false,
+
+    // Disable slow script dialogues
+    'dom.max_chrome_script_run_time': 0,
+    'dom.max_script_run_time': 0,
+
+    // Only load extensions from the application and user profile
+    // AddonManager.SCOPE_PROFILE + AddonManager.SCOPE_APPLICATION
+    'extensions.autoDisableScopes': 0,
+    'extensions.enabledScopes': 5,
+
+    // Disable metadata caching for installed add-ons by default
+    'extensions.getAddons.cache.enabled': false,
+
+    // Disable installing any distribution extensions or add-ons.
+    'extensions.installDistroAddons': false,
+
+    // Disabled screenshots extension
+    'extensions.screenshots.disabled': true,
+
+    // Turn off extension updates so they do not bother tests
+    'extensions.update.enabled': false,
+
+    // Turn off extension updates so they do not bother tests
+    'extensions.update.notifyUser': false,
+
+    // Make sure opening about:addons will not hit the network
+    'extensions.webservice.discoverURL': `http://${server}/dummy/discoveryURL`,
+
+    // Allow the application to have focus even it runs in the background
+    'focusmanager.testmode': true,
+
+    // Disable useragent updates
+    'general.useragent.updates.enabled': false,
+
+    // Always use network provider for geolocation tests so we bypass the
+    // macOS dialog raised by the corelocation provider
+    'geo.provider.testing': true,
+
+    // Do not scan Wifi
+    'geo.wifi.scan': false,
+
+    // No hang monitor
+    'hangmonitor.timeout': 0,
+
+    // Show chrome errors and warnings in the error console
+    'javascript.options.showInConsole': true,
+
+    // Disable download and usage of OpenH264: and Widevine plugins
+    'media.gmp-manager.updateEnabled': false,
+
+    // Disable the GFX sanity window
+    'media.sanity-test.disabled': true,
+
+    // Disable experimental feature that is only available in Nightly
+    'network.cookie.sameSite.laxByDefault': false,
+
+    // Do not prompt for temporary redirects
+    'network.http.prompt-temp-redirect': false,
+
+    // Disable speculative connections so they are not reported as leaking
+    // when they are hanging around
+    'network.http.speculative-parallel-limit': 0,
+
+    // Do not automatically switch between offline and online
+    'network.manage-offline-status': false,
+
+    // Make sure SNTP requests do not hit the network
+    'network.sntp.pools': server,
+
+    // Disable Flash.
+    'plugin.state.flash': 0,
+
+    'privacy.trackingprotection.enabled': false,
+
+    // Can be removed once Firefox 89 is no longer supported
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=1710839
+    'remote.enabled': true,
+
+    // Don't do network connections for mitm priming
+    'security.certerrors.mitm.priming.enabled': false,
+
+    // Local documents have access to all other local documents,
+    // including directory listings
+    'security.fileuri.strict_origin_policy': false,
+
+    // Do not wait for the notification button security delay
+    'security.notification_enable_delay': 0,
+
+    // Ensure blocklist updates do not hit the network
+    'services.settings.server': `http://${server}/dummy/blocklist/`,
+
+    // Do not automatically fill sign-in forms with known usernames and
+    // passwords
+    'signon.autofillForms': false,
+
+    // Disable password capture, so that tests that include forms are not
+    // influenced by the presence of the persistent doorhanger notification
+    'signon.rememberSignons': false,
+
+    // Disable first-run welcome page
+    'startup.homepage_welcome_url': 'about:blank',
+
+    // Disable first-run welcome page
+    'startup.homepage_welcome_url.additional': '',
+
+    // Disable browser animations (tabs, fullscreen, sliding alerts)
+    'toolkit.cosmeticAnimations.enabled': false,
+
+    // Prevent starting into safe mode after application crashes
+    'toolkit.startup.max_resumed_crashes': -1,
+  };
+
+  return Object.assign(defaultPrefs, extraPrefs);
+}
+
+/**
+ * Populates the user.js file with custom preferences as needed to allow
+ * Firefox's CDP support to properly function. These preferences will be
+ * automatically copied over to prefs.js during startup of Firefox. To be
+ * able to restore the original values of preferences a backup of prefs.js
+ * will be created.
+ *
+ * @param prefs - List of preferences to add.
+ * @param profilePath - Firefox profile to write the preferences to.
+ */
+async function writePreferences(options: ProfileOptions): Promise<void> {
+  const prefsPath = path.join(options.path, 'prefs.js');
+  const lines = Object.entries(options.preferences).map(([key, value]) => {
+    return `user_pref(${JSON.stringify(key)}, ${JSON.stringify(value)});`;
+  });
+
+  // Use allSettled to prevent corruption
+  const result = await Promise.allSettled([
+    fs.promises.writeFile(path.join(options.path, 'user.js'), lines.join('\n')),
+    // Create a backup of the preferences file if it already exitsts.
+    fs.promises.access(prefsPath, fs.constants.F_OK).then(
+      async () => {
+        await fs.promises.copyFile(
+          prefsPath,
+          path.join(options.path, 'prefs.js.playwright')
+        );
+      },
+      // Swallow only if file does not exist
+      () => {}
+    ),
+  ]);
+  for (const command of result) {
+    if (command.status === 'rejected') {
+      throw command.reason;
+    }
+  }
+}
diff --git a/packages/playwright-core/src/server/browserType.ts b/packages/playwright-core/src/server/browserType.ts
index abc15a20f4..ec8524c247 100644
--- a/packages/playwright-core/src/server/browserType.ts
+++ b/packages/playwright-core/src/server/browserType.ts
@@ -192,6 +192,7 @@ export abstract class BrowserType extends SdkObject {
       userDataDir = await fs.promises.mkdtemp(path.join(os.tmpdir(), `playwright_${this._name}dev_profile-`));
       tempDirectories.push(userDataDir);
     }
+    await this.prepareUserDataDir(options, userDataDir);
 
     const browserArguments = [];
     if (ignoreAllDefaultArgs)
@@ -328,6 +329,9 @@ export abstract class BrowserType extends SdkObject {
     return undefined;
   }
 
+  async prepareUserDataDir(options: types.LaunchOptions, userDataDir: string): Promise<void> {
+  }
+
   abstract defaultArgs(options: types.LaunchOptions, isPersistent: boolean, userDataDir: string): string[];
   abstract connectToTransport(transport: ConnectionTransport, options: BrowserOptions): Promise<Browser>;
   abstract amendEnvironment(env: Env, userDataDir: string, executable: string, browserArguments: string[]): Env;