diff --git a/packages/wxt/src/core/resolve-config.ts b/packages/wxt/src/core/resolve-config.ts
index d1489f47..211d425b 100644
--- a/packages/wxt/src/core/resolve-config.ts
+++ b/packages/wxt/src/core/resolve-config.ts
@@ -227,6 +227,7 @@ export async function resolveConfig(
     userConfigMetadata: userConfigMetadata ?? {},
     alias,
     experimental: defu(mergedConfig.experimental, {}),
+    suppressWarnings: mergedConfig.suppressWarnings ?? {},
     dev: {
       server: devServerConfig,
       reloadCommand,
diff --git a/packages/wxt/src/core/utils/__tests__/manifest.test.ts b/packages/wxt/src/core/utils/__tests__/manifest.test.ts
index fffd2e80..5e0ffbfa 100644
--- a/packages/wxt/src/core/utils/__tests__/manifest.test.ts
+++ b/packages/wxt/src/core/utils/__tests__/manifest.test.ts
@@ -1578,6 +1578,9 @@ describe('Manifest Utils', () => {
               // @ts-ignore: Purposefully removing version from fake object
               version: null,
             },
+            suppressWarnings: {
+              firefoxDataCollection: true,
+            },
           },
         });
 
@@ -2011,6 +2014,9 @@ describe('Manifest Utils', () => {
             manifest: {
               manifest_version: 3,
             },
+            suppressWarnings: {
+              firefoxDataCollection: true,
+            },
           },
         });
 
diff --git a/packages/wxt/src/core/utils/manifest.ts b/packages/wxt/src/core/utils/manifest.ts
index eef0c78c..24ee0087 100644
--- a/packages/wxt/src/core/utils/manifest.ts
+++ b/packages/wxt/src/core/utils/manifest.ts
@@ -115,6 +115,20 @@ export async function generateManifest(
       ? undefined
       : versionName;
 
+  // Warn if building for Firefox without data_collection_permissions
+  if (
+    wxt.config.browser === 'firefox' &&
+    !userManifest.browser_specific_settings?.gecko
+      ?.data_collection_permissions &&
+    !wxt.config.suppressWarnings?.firefoxDataCollection
+  ) {
+    wxt.logger.warn(
+      'Firefox requires `data_collection_permissions` for new extensions from November 3, 2025. Existing extensions are exempt for now.\n' +
+        'For more details, see: https://extensionworkshop.com/documentation/develop/firefox-builtin-data-consent/\n' +
+        'To suppress this warning, set `suppressWarnings.firefoxDataCollection` to `true` in your wxt config.\n',
+    );
+  }
+
   addEntrypoints(manifest, entrypoints, buildOutput);
 
   if (wxt.config.browser === 'firefox') {
diff --git a/packages/wxt/src/core/utils/testing/fake-objects.ts b/packages/wxt/src/core/utils/testing/fake-objects.ts
index ddae3af7..9a97e666 100644
--- a/packages/wxt/src/core/utils/testing/fake-objects.ts
+++ b/packages/wxt/src/core/utils/testing/fake-objects.ts
@@ -26,7 +26,7 @@ import { vi } from 'vitest';
 import { setWxtForTesting } from '../../wxt';
 import type { Browser } from '@wxt-dev/browser';
 
-faker.seed(import.meta.test.SEED);
+faker.seed(import.meta.env.TEST_SEED);
 
 type DeepPartial<T> = T extends object
   ? {
@@ -302,6 +302,7 @@ export const fakeResolvedConfig = fakeObjectCreator<ResolvedConfig>(() => {
     hooks: {},
     vite: () => ({}),
     plugins: [],
+    suppressWarnings: {},
   };
 });
 
diff --git a/packages/wxt/src/types.ts b/packages/wxt/src/types.ts
index 968b4f5b..9c9f4d09 100644
--- a/packages/wxt/src/types.ts
+++ b/packages/wxt/src/types.ts
@@ -143,6 +143,25 @@ export interface InlineConfig {
    * function that returns an object or promise.
    */
   manifest?: UserManifest | Promise<UserManifest> | UserManifestFn;
+  /**
+   * Suppress specific warnings during the build process.
+   *
+   * @example
+   *   ```ts
+   *   export default defineConfig({
+   *     suppressWarnings: {
+   *       firefoxDataCollection: true,
+   *     },
+   *   })
+   *   ```;
+   */
+  suppressWarnings?: {
+    /**
+     * Suppress warnings for:
+     * https://extensionworkshop.com/documentation/develop/firefox-builtin-data-consent
+     */
+    firefoxDataCollection?: boolean;
+  };
   /**
    * Configure browser startup. Options set here can be overridden in a
    * `web-ext.config.ts` file.
@@ -944,6 +963,41 @@ export type ResolvedPerBrowserOptions<T, TOmitted extends keyof T = never> = {
     : T[key];
 } & { [key in TOmitted]: T[key] };
 
+/**
+ * Firefox data collection permission types for personal data. See:
+ * https://extensionworkshop.com/documentation/develop/firefox-builtin-data-consent/#specifying-data-types
+ */
+export type FirefoxDataCollectionType =
+  | 'locationInfo'
+  | 'browsingActivity'
+  | 'websiteContent'
+  | 'websiteActivity'
+  | 'searchTerms'
+  | 'bookmarksInfo'
+  | 'healthInfo'
+  | 'contactInfo'
+  | 'socialInfo'
+  | (string & {});
+
+/**
+ * Firefox data collection permissions configuration. See:
+ * https://extensionworkshop.com/documentation/develop/firefox-builtin-data-consent/#specifying-data-types
+ */
+export interface FirefoxDataCollectionPermissions {
+  /**
+   * Required data collection permissions. Users must opt in to use the
+   * extension. Can include personal data types or "none" to explicitly indicate
+   * no data collection.
+   */
+  required?: Array<FirefoxDataCollectionType | 'none'>;
+  /**
+   * Optional data collection permissions. Users can opt in after installation.
+   * Can include personal data types or "technicalAndInteraction" (which can
+   * only be optional).
+   */
+  optional?: Array<FirefoxDataCollectionType | 'technicalAndInteraction'>;
+}
+
 /**
  * Manifest customization available in the `wxt.config.ts` file. You cannot
  * configure entrypoints here, they are configured inline.
@@ -982,6 +1036,11 @@ export type UserManifest = {
       strict_min_version?: string;
       strict_max_version?: string;
       update_url?: string;
+      /**
+       * Firefox data collection permissions configuration. See:
+       * https://extensionworkshop.com/documentation/develop/firefox-builtin-data-consent/#specifying-data-types
+       */
+      data_collection_permissions?: FirefoxDataCollectionPermissions;
     };
     gecko_android?: {
       strict_min_version?: string;
@@ -1442,6 +1501,8 @@ export interface ResolvedConfig {
   /** Import aliases to absolute paths. */
   alias: Record<string, string>;
   experimental: {};
+  /** List of warning identifiers to suppress during the build process. */
+  suppressWarnings: { firefoxDataCollection?: boolean };
   dev: {
     /** Only defined during dev command */
     server?: {
diff --git a/packages/wxt/vitest.config.ts b/packages/wxt/vitest.config.ts
index 0c25b962..733e7b92 100644
--- a/packages/wxt/vitest.config.ts
+++ b/packages/wxt/vitest.config.ts
@@ -19,7 +19,7 @@ export default defineConfig({
       ignored: '**/dist/**',
     },
   },
-  plugins: [RandomSeed()],
+  plugins: [RandomSeed({ define: 'import.meta.env.TEST_SEED' })],
   resolve: {
     alias: {
       'wxt/testing': path.resolve('src/testing'),