diff --git a/.wp-env.json b/.wp-env.json
index ccd1231aa28b2..41ecee8042bb1 100644
--- a/.wp-env.json
+++ b/.wp-env.json
@@ -3,7 +3,7 @@
 	"plugins": [
 		"."
 	],
-	"themes": [ "WordPress/theme-experiments/tt1-blocks" ],
+	"themes": [ "WordPress/theme-experiments/twentytwentyone-blocks" ],
 	"env": {
 		"tests": {
 			"mappings": {
diff --git a/packages/e2e-tests/specs/experiments/blocks/post-title.test.js b/packages/e2e-tests/specs/experiments/blocks/post-title.test.js
index 6bd00baba6d82..5e307541ff9cd 100644
--- a/packages/e2e-tests/specs/experiments/blocks/post-title.test.js
+++ b/packages/e2e-tests/specs/experiments/blocks/post-title.test.js
@@ -11,7 +11,7 @@ import {
 
 describe( 'Post Title block', () => {
 	beforeAll( async () => {
-		await activateTheme( 'tt1-blocks' );
+		await activateTheme( 'twentytwentyone-blocks' );
 	} );
 
 	afterAll( async () => {
diff --git a/packages/e2e-tests/specs/experiments/multi-entity-editing.test.js b/packages/e2e-tests/specs/experiments/multi-entity-editing.test.js
index 845b2e4044e98..3a8e75b31158c 100644
--- a/packages/e2e-tests/specs/experiments/multi-entity-editing.test.js
+++ b/packages/e2e-tests/specs/experiments/multi-entity-editing.test.js
@@ -127,7 +127,7 @@ const removeErrorMocks = () => {
 
 describe( 'Multi-entity editor states', () => {
 	beforeAll( async () => {
-		await activateTheme( 'tt1-blocks' );
+		await activateTheme( 'twentytwentyone-blocks' );
 		await trashAllPosts( 'wp_template' );
 		await trashAllPosts( 'wp_template_part' );
 	} );
diff --git a/packages/e2e-tests/specs/experiments/multi-entity-saving.test.js b/packages/e2e-tests/specs/experiments/multi-entity-saving.test.js
index 5d989d8ced76d..1cb3f8aaf773b 100644
--- a/packages/e2e-tests/specs/experiments/multi-entity-saving.test.js
+++ b/packages/e2e-tests/specs/experiments/multi-entity-saving.test.js
@@ -45,7 +45,7 @@ describe( 'Multi-entity save flow', () => {
 	};
 
 	beforeAll( async () => {
-		await activateTheme( 'tt1-blocks' );
+		await activateTheme( 'twentytwentyone-blocks' );
 		await trashAllPosts( 'wp_template' );
 		await trashAllPosts( 'wp_template_part' );
 	} );
diff --git a/packages/e2e-tests/specs/experiments/post-editor-template-mode.test.js b/packages/e2e-tests/specs/experiments/post-editor-template-mode.test.js
index 140f567e4d74f..31a795a1b2d2f 100644
--- a/packages/e2e-tests/specs/experiments/post-editor-template-mode.test.js
+++ b/packages/e2e-tests/specs/experiments/post-editor-template-mode.test.js
@@ -13,7 +13,7 @@ import {
 
 describe( 'Post Editor Template mode', () => {
 	beforeAll( async () => {
-		await activateTheme( 'tt1-blocks' );
+		await activateTheme( 'twentytwentyone-blocks' );
 		await trashAllPosts( 'wp_template' );
 		await trashAllPosts( 'wp_template_part' );
 	} );
diff --git a/packages/e2e-tests/specs/experiments/template-part.test.js b/packages/e2e-tests/specs/experiments/template-part.test.js
index 112f6bfc59681..e531067f277aa 100644
--- a/packages/e2e-tests/specs/experiments/template-part.test.js
+++ b/packages/e2e-tests/specs/experiments/template-part.test.js
@@ -21,7 +21,7 @@ import { navigationPanel } from '../../experimental-features';
 
 describe( 'Template Part', () => {
 	beforeAll( async () => {
-		await activateTheme( 'tt1-blocks' );
+		await activateTheme( 'twentytwentyone-blocks' );
 		await trashAllPosts( 'wp_template' );
 		await trashAllPosts( 'wp_template_part' );
 	} );
diff --git a/packages/e2e-tests/specs/performance/site-editor.test.js b/packages/e2e-tests/specs/performance/site-editor.test.js
index b638c1db1c302..ef468fe0453e9 100644
--- a/packages/e2e-tests/specs/performance/site-editor.test.js
+++ b/packages/e2e-tests/specs/performance/site-editor.test.js
@@ -18,7 +18,7 @@ jest.setTimeout( 1000000 );
 
 describe( 'Site Editor Performance', () => {
 	beforeAll( async () => {
-		await activateTheme( 'tt1-blocks' );
+		await activateTheme( 'twentytwentyone-blocks' );
 		await trashAllPosts( 'wp_template' );
 		await trashAllPosts( 'wp_template', 'auto-draft' );
 		await trashAllPosts( 'wp_template_part' );