diff --git a/docs/api/README.md b/docs/api/README.md
index f57c88c6..a6ea7409 100644
--- a/docs/api/README.md
+++ b/docs/api/README.md
@@ -312,13 +312,13 @@ limitations under the License.
 
 ### createRunner
 
-▸ **createRunner**(`flow`, `extension?`): `Promise`<[`Runner`](classes/Runner.md)\>
+▸ **createRunner**(`flow?`, `extension?`): `Promise`<[`Runner`](classes/Runner.md)\>
 
 #### Parameters
 
 | Name         | Type                                            |
 | :----------- | :---------------------------------------------- |
-| `flow`       | [`UserFlow`](interfaces/Schema.UserFlow.md)     |
+| `flow?`      | [`UserFlow`](interfaces/Schema.UserFlow.md)     |
 | `extension?` | [`RunnerExtension`](classes/RunnerExtension.md) |
 
 #### Returns
@@ -327,7 +327,7 @@ limitations under the License.
 
 #### Defined in
 
-[Runner.ts:79](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L79)
+[Runner.ts:92](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L92)
 
 ---
 
diff --git a/docs/api/classes/Runner.md b/docs/api/classes/Runner.md
index 9290de77..30622e74 100644
--- a/docs/api/classes/Runner.md
+++ b/docs/api/classes/Runner.md
@@ -4,12 +4,36 @@
 
 ## Table of contents
 
+### Accessors
+
+- [flow](Runner.md#flow)
+
 ### Methods
 
 - [abort](Runner.md#abort)
 - [run](Runner.md#run)
 - [runStep](Runner.md#runstep)
 
+## Accessors
+
+### flow
+
+• `set` **flow**(`flow`): `void`
+
+#### Parameters
+
+| Name   | Type                                           |
+| :----- | :--------------------------------------------- |
+| `flow` | [`UserFlow`](../interfaces/Schema.UserFlow.md) |
+
+#### Returns
+
+`void`
+
+#### Defined in
+
+[Runner.ts:47](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L47)
+
 ## Methods
 
 ### abort
@@ -22,7 +46,7 @@
 
 #### Defined in
 
-[Runner.ts:44](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L44)
+[Runner.ts:43](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L43)
 
 ---
 
@@ -40,7 +64,7 @@ whether all the steps are run or the execution is aborted
 
 #### Defined in
 
-[Runner.ts:56](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L56)
+[Runner.ts:63](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L63)
 
 ---
 
@@ -48,6 +72,9 @@ whether all the steps are run or the execution is aborted
 
 ▸ **runStep**(`step`): `Promise`<`void`\>
 
+Runs the provided `step` with `beforeEachStep` and `afterEachStep` hooks.
+Parameters from the `flow` apply if the `flow` is set.
+
 #### Parameters
 
 | Name   | Type                                |
@@ -60,4 +87,4 @@ whether all the steps are run or the execution is aborted
 
 #### Defined in
 
-[Runner.ts:48](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L48)
+[Runner.ts:55](https://github.com/puppeteer/replay/blob/main/src/Runner.ts#L55)
diff --git a/src/Runner.ts b/src/Runner.ts
index bb1fffc2..f765fe09 100644
--- a/src/Runner.ts
+++ b/src/Runner.ts
@@ -29,15 +29,14 @@ async function _runStepWithHooks(
 }
 
 export class Runner {
-  #flow: UserFlow;
+  #flow?: UserFlow;
   #extension: RunnerExtension;
   #aborted: boolean = false;
 
   /**
    * @internal
    */
-  constructor(flow: UserFlow, extension: RunnerExtension) {
-    this.#flow = flow;
+  constructor(extension: RunnerExtension) {
     this.#extension = extension;
   }
 
@@ -45,6 +44,14 @@ export class Runner {
     this.#aborted = true;
   }
 
+  set flow(flow: UserFlow) {
+    this.#flow = flow;
+  }
+
+  /**
+   * Runs the provided `step` with `beforeEachStep` and `afterEachStep` hooks.
+   * Parameters from the `flow` apply if the `flow` is set.
+   */
   async runStep(step: Step): Promise<void> {
     await _runStepWithHooks(this.#extension, step);
   }
@@ -54,36 +61,47 @@ export class Runner {
    * @returns whether all the steps are run or the execution is aborted
    */
   async run(): Promise<boolean> {
+    if (!this.#flow) {
+      throw new Error(
+        'Set the flow on the runner instance before calling `run`.'
+      );
+    }
+
+    const flow = this.#flow;
+
     this.#aborted = false;
 
-    await this.#extension.beforeAllSteps?.(this.#flow);
+    await this.#extension.beforeAllSteps?.(flow);
 
     if (this.#aborted) {
       return false;
     }
 
-    for (const step of this.#flow.steps) {
+    for (const step of flow.steps) {
       if (this.#aborted) {
-        await this.#extension.afterAllSteps?.(this.#flow);
+        await this.#extension.afterAllSteps?.(flow);
         return false;
       }
-      await _runStepWithHooks(this.#extension, step, this.#flow);
+      await _runStepWithHooks(this.#extension, step, flow);
     }
 
-    await this.#extension.afterAllSteps?.(this.#flow);
+    await this.#extension.afterAllSteps?.(flow);
 
     return true;
   }
 }
 
 export async function createRunner(
-  flow: UserFlow,
+  flow?: UserFlow,
   extension?: RunnerExtension
 ) {
-  return new Runner(
-    flow,
+  const runner = new Runner(
     extension ?? (await createPuppeteerRunnerOwningBrowserExtension())
   );
+  if (flow) {
+    runner.flow = flow;
+  }
+  return runner;
 }
 
 async function createPuppeteerRunnerOwningBrowserExtension() {
diff --git a/src/lighthouse/LighthouseRunnerExtension.ts b/src/lighthouse/LighthouseRunnerExtension.ts
index e5244833..2a6811bd 100644
--- a/src/lighthouse/LighthouseRunnerExtension.ts
+++ b/src/lighthouse/LighthouseRunnerExtension.ts
@@ -52,7 +52,7 @@ export class LighthouseRunnerExtension extends PuppeteerRunnerExtension {
     });
   }
 
-  override async beforeEachStep(step: Step, flow: UserFlow) {
+  override async beforeEachStep(step: Step, flow?: UserFlow) {
     await super.beforeEachStep?.(step, flow);
     if (step.type === StepType.SetViewport) return;
 
@@ -69,7 +69,7 @@ export class LighthouseRunnerExtension extends PuppeteerRunnerExtension {
     }
   }
 
-  override async afterEachStep(step: Step, flow: UserFlow) {
+  override async afterEachStep(step: Step, flow?: UserFlow) {
     if (this.#isNavigationRunning) {
       await this.#lhFlow.endNavigation();
       this.#isNavigationRunning = false;
diff --git a/test/runner.test.ts b/test/runner.test.ts
index c1cbe977..f46e50f6 100644
--- a/test/runner.test.ts
+++ b/test/runner.test.ts
@@ -939,11 +939,7 @@ describe('Runner', () => {
 
   it('should replay individual steps', async () => {
     const runner = await createRunner(
-      {
-        title: 'Test Recording',
-        timeout: 3000,
-        steps: [],
-      },
+      undefined,
       new PuppeteerRunnerExtension(browser, page)
     );
     await runner.runStep({