diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/index.ts b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/index.ts
new file mode 100644
index 000000000000..abc4a78578af
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/index.ts
@@ -0,0 +1,46 @@
+import { DurableObject } from 'cloudflare:workers';
+
+interface Env {
+  SENTRY_DSN: string;
+  TEST_DURABLE_OBJECT: DurableObjectNamespace<TestDurableObject>;
+  TAIL: Fetcher;
+}
+
+export class TestDurableObject extends DurableObject<Env> {
+  async fetch(): Promise<Response> {
+    return new Response('OK');
+  }
+
+  async ping(): Promise<string> {
+    return 'pong';
+  }
+
+  async setAlarm(): Promise<void> {
+    await this.ctx.storage.setAlarm(Date.now());
+  }
+
+  async alarm(): Promise<void> {}
+}
+
+export default {
+  async fetch(request: Request, env: Env): Promise<Response> {
+    const url = new URL(request.url);
+
+    if (url.pathname === '/invocations') {
+      return env.TAIL.fetch(request);
+    }
+
+    const stub = env.TEST_DURABLE_OBJECT.get(env.TEST_DURABLE_OBJECT.idFromName(url.pathname));
+
+    if (url.pathname === '/rpc') {
+      return new Response(await stub.ping());
+    }
+
+    if (url.pathname === '/alarm') {
+      await stub.setAlarm();
+      return new Response('Alarm scheduled');
+    }
+
+    return stub.fetch(request);
+  },
+} satisfies ExportedHandler<Env>;
diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/instrument.server.ts b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/instrument.server.ts
new file mode 100644
index 000000000000..e577550ae0b8
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/instrument.server.ts
@@ -0,0 +1,6 @@
+import { defineCloudflareOptions } from '@sentry/cloudflare';
+
+export default defineCloudflareOptions((env: { SENTRY_DSN: string }) => ({
+  dsn: env.SENTRY_DSN,
+  tracesSampleRate: 1.0,
+}));
diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/tail.ts b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/tail.ts
new file mode 100644
index 000000000000..865d977d6a5c
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/tail.ts
@@ -0,0 +1,26 @@
+interface Invocation {
+  trigger: string;
+  durationMs: number;
+}
+
+const invocations: Invocation[] = [];
+
+export default {
+  async tail(events: TraceItem[]): Promise<void> {
+    // `wallTime` is always 0 in local dev, so the duration ends when the tail event arrives.
+    const receivedAt = Date.now();
+
+    for (const { event, eventTimestamp, executionModel } of events) {
+      if (executionModel !== 'durableObject' || !event || eventTimestamp === null) {
+        continue;
+      }
+
+      const trigger = 'rpcMethod' in event ? event.rpcMethod : 'scheduledTime' in event ? 'alarm' : 'fetch';
+      invocations.push({ trigger, durationMs: receivedAt - eventTimestamp });
+    }
+  },
+
+  async fetch(): Promise<Response> {
+    return Response.json(invocations);
+  },
+} satisfies ExportedHandler;
diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/test.ts b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/test.ts
new file mode 100644
index 000000000000..11db17ae2348
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/test.ts
@@ -0,0 +1,46 @@
+import { join } from 'node:path';
+import { expect, it, vi } from 'vitest';
+import { createRunner } from '../../../runner';
+
+interface Invocation {
+  trigger: string;
+  durationMs: number;
+}
+
+// Regression test for https://github.com/getsentry/sentry-javascript/issues/25489
+// workerd keeps a Durable Object invocation open until its pending timers fire, so an SDK timer
+// that is still pending when the method returns makes the invocation longer, and billed.
+it('does not keep Durable Object invocations open after the method returns', async ({ signal }) => {
+  // The tail worker must run in the same `wrangler dev` process to receive the tail events.
+  const runner = createRunner(__dirname)
+    .withWranglerArgs('--config', join(__dirname, 'wrangler-tail.jsonc'))
+    .start(signal);
+
+  await runner.makeRequest('get', '/fetch');
+  await runner.makeRequest('get', '/rpc');
+  await runner.makeRequest('get', '/alarm');
+
+  const { fetchInvocation, rpcInvocation, alarmInvocation } = await vi.waitFor(
+    async () => {
+      const invocations = (await runner.makeRequest<Invocation[]>('get', '/invocations')) ?? [];
+      const result = {
+        fetchInvocation: invocations.find(invocation => invocation.trigger === 'fetch'),
+        rpcInvocation: invocations.find(invocation => invocation.trigger === 'ping'),
+        alarmInvocation: invocations.find(invocation => invocation.trigger === 'alarm'),
+      };
+
+      expect(result.fetchInvocation).toBeDefined();
+      expect(result.rpcInvocation).toBeDefined();
+      expect(result.alarmInvocation).toBeDefined();
+
+      return result;
+    },
+    { timeout: 10_000, interval: 100 },
+  );
+
+  // An invocation takes a few ms locally. The limit leaves room for slow CI machines and still
+  // fails for a 500 ms timer.
+  expect(fetchInvocation?.durationMs).toBeLessThan(250);
+  expect(rpcInvocation?.durationMs).toBeLessThan(250);
+  expect(alarmInvocation?.durationMs).toBeLessThan(250);
+});
diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/vite.config.mts b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/vite.config.mts
new file mode 100644
index 000000000000..005f4448f6cb
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/vite.config.mts
@@ -0,0 +1,7 @@
+import { cloudflare } from '@cloudflare/vite-plugin';
+import { sentryCloudflareVitePlugin } from '@sentry/cloudflare/vite';
+import { defineConfig } from 'vite';
+
+export default defineConfig({
+  plugins: [cloudflare(), sentryCloudflareVitePlugin()],
+});
diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/wrangler-tail.jsonc b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/wrangler-tail.jsonc
new file mode 100644
index 000000000000..88d1d67db66f
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/wrangler-tail.jsonc
@@ -0,0 +1,6 @@
+{
+  "$schema": "../../../node_modules/wrangler/config-schema.json",
+  "name": "durableobject-invocation-duration-tail",
+  "main": "tail.ts",
+  "compatibility_date": "2025-06-17",
+}
diff --git a/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/wrangler.jsonc b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/wrangler.jsonc
new file mode 100644
index 000000000000..f37ce093d9ce
--- /dev/null
+++ b/dev-packages/cloudflare-integration-tests/suites/durableobject/invocation-duration/wrangler.jsonc
@@ -0,0 +1,13 @@
+{
+  "$schema": "../../../node_modules/wrangler/config-schema.json",
+  "name": "durableobject-invocation-duration",
+  "main": "index.ts",
+  "compatibility_date": "2025-06-17",
+  "compatibility_flags": ["nodejs_compat"],
+  "durable_objects": {
+    "bindings": [{ "name": "TEST_DURABLE_OBJECT", "class_name": "TestDurableObject" }],
+  },
+  "migrations": [{ "tag": "v1", "new_sqlite_classes": ["TestDurableObject"] }],
+  "services": [{ "binding": "TAIL", "service": "durableobject-invocation-duration-tail" }],
+  "tail_consumers": [{ "service": "durableobject-invocation-duration-tail" }],
+}