diff --git a/packages/async-ssr-manager/src/index.ts b/packages/async-ssr-manager/src/index.ts
index 5d510c7e4..497cd2b9b 100644
--- a/packages/async-ssr-manager/src/index.ts
+++ b/packages/async-ssr-manager/src/index.ts
@@ -37,7 +37,7 @@ export interface AsyncSsrManagerV1 {
    *
    * @param render A render function that is called for each render pass.
    */
-  renderUntilCompleted(render: () => string): Promise<string>;
+  renderUntilCompleted(render: () => Promise<string> | string): Promise<string>;
 
   /**
    * This method is intended for consumers, i.e. Feature Apps and Feature
diff --git a/packages/async-ssr-manager/src/internal/async-ssr-manager.ts b/packages/async-ssr-manager/src/internal/async-ssr-manager.ts
index 852de700a..ccf82c825 100644
--- a/packages/async-ssr-manager/src/internal/async-ssr-manager.ts
+++ b/packages/async-ssr-manager/src/internal/async-ssr-manager.ts
@@ -16,7 +16,9 @@ export class AsyncSsrManager implements AsyncSsrManagerV1 {
     private readonly timeout?: number
   ) {}
 
-  public async renderUntilCompleted(render: () => string): Promise<string> {
+  public async renderUntilCompleted(
+    render: () => Promise<string> | string
+  ): Promise<string> {
     const renderPromise = this.renderingLoop(render);
 
     if (typeof this.timeout !== 'number') {
@@ -36,8 +38,10 @@ export class AsyncSsrManager implements AsyncSsrManagerV1 {
     this.asyncOperations.add(asyncOperation);
   }
 
-  private async renderingLoop(render: () => string): Promise<string> {
-    let html = render();
+  private async renderingLoop(
+    render: () => Promise<string> | string
+  ): Promise<string> {
+    let html = await render();
 
     while (this.asyncOperations.size > 0) {
       while (this.asyncOperations.size > 0) {
@@ -54,7 +58,7 @@ export class AsyncSsrManager implements AsyncSsrManagerV1 {
         await Promise.all(asyncOperationsSnapshot);
       }
 
-      html = render();
+      html = await render();
     }
 
     return html;