diff --git a/packages/browser-playwright/src/playwright.ts b/packages/browser-playwright/src/playwright.ts
index cbe09c45b..b945a5da2 100644
--- a/packages/browser-playwright/src/playwright.ts
+++ b/packages/browser-playwright/src/playwright.ts
@@ -246,6 +246,7 @@ export class PlaywrightBrowserProvider implements BrowserProvider {
 
   private browserPromise: Promise<Browser> | null = null
   private closing = false
+  private armedContexts = new WeakMap<BrowserContext, Promise<void>>()
 
   public tracingContexts: Set<string> = new Set()
   public pendingTraces: Map<string, string> = new Map()
@@ -390,6 +391,54 @@ export class PlaywrightBrowserProvider implements BrowserProvider {
     return this.browserPromise
   }
 
+  private armInterception(page: Page): Promise<void> {
+    if (this.browserName !== 'chromium') {
+      return Promise.resolve()
+    }
+    const context = page.context()
+    const armed =
+      this.armedContexts.get(context) ??
+      this.probeInterception(page).catch((error) => {
+        this.armedContexts.delete(context)
+        throw error
+      })
+    this.armedContexts.set(context, armed)
+    return armed
+  }
+
+  private async probeInterception(page: Page): Promise<void> {
+    const probeUrl = '/__vitest_interception_probe__'
+    const probePattern = `**${probeUrl}`
+    const context = page.context()
+    await context.route(probePattern, (route) =>
+      route.fulfill({
+        status: 204,
+        headers: { 'x-vitest-probe': '1' },
+      }),
+    )
+    const deadline = Date.now() + 5_000
+    while (Date.now() < deadline) {
+      const intercepted = await page
+        .evaluate(
+          (url) =>
+            fetch(url, { cache: 'no-store', signal: AbortSignal.timeout(1_000) }).then(
+              (r) => r.headers.has('x-vitest-probe'),
+              () => false,
+            ),
+          probeUrl,
+        )
+        .catch(() => false)
+      if (intercepted) {
+        return
+      }
+      await new Promise((resolve) => setTimeout(resolve, 10))
+    }
+    await context.unroute(probePattern)
+    throw new Error(
+      `Cannot verify that ${this.browserName} request interception is active after 5s; module mocks would not apply reliably (#8339)`,
+    )
+  }
+
   private createMocker(): BrowserModuleMocker {
     const idPredicates = new Map<string, (url: URL) => boolean>()
     const sessionIds = new Map<string, Set<string>>()
@@ -434,6 +483,7 @@ export class PlaywrightBrowserProvider implements BrowserProvider {
     return {
       register: async (sessionId: string, module: MockedModule): Promise<void> => {
         const page = this.getPage(sessionId)
+        await this.armInterception(page)
         const { url: moduleUrl, predicate } = createPredicate(module.url)
         const key = predicateKey(sessionId, moduleUrl)
         const existingPredicate = idPredicates.get(key)
diff --git a/test/browser/fixtures/mocking/interception-probe.test.ts b/test/browser/fixtures/mocking/interception-probe.test.ts
new file mode 100644
index 000000000..29328c620
--- /dev/null
+++ b/test/browser/fixtures/mocking/interception-probe.test.ts
@@ -0,0 +1,9 @@
+import { expect, test, vi } from 'vitest'
+import { server } from 'vitest/browser'
+
+vi.mock(import('./src/mocks_factory'))
+
+test.runIf(server.config.name === 'chromium')('request interception is live once a mock is registered', async () => {
+  const response = await fetch('/__vitest_interception_probe__', { cache: 'no-store' })
+  expect(response.headers.get('x-vitest-probe')).toBe('1')
+})