diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index 9200203896..89941a6ff9 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -257,6 +257,9 @@ jobs:
       - name: Run tests as a multisite install
         run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c tests/phpunit/multisite.xml
 
+      - name: Run AJAX tests as a multisite install
+        run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c tests/phpunit/multisite.xml --group ajax
+
       - name: Run ms-files tests as a multisite install
         run: npm run test:${{ env.PHPUNIT_SCRIPT }} -- --verbose -c tests/phpunit/multisite.xml --group ms-files
 
diff --git a/Gruntfile.js b/Gruntfile.js
index 3c8706207a..2d0b8b295c 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -673,6 +673,10 @@ module.exports = function(grunt) {
 				cmd: 'phpunit',
 				args: ['--verbose', '-c', 'tests/phpunit/multisite.xml']
 			},
+			'ms-ajax': {
+				cmd: 'phpunit',
+				args: ['--verbose', '-c', 'tests/phpunit/multisite.xml', '--group', 'ajax']
+			},
 			'ms-files': {
 				cmd: 'phpunit',
 				args: ['--verbose', '-c', 'tests/phpunit/multisite.xml', '--group', 'ms-files']
diff --git a/tests/phpunit/tests/ajax/Attachments.php b/tests/phpunit/tests/ajax/Attachments.php
index 0f3b19b203..0b2cb09451 100644
--- a/tests/phpunit/tests/ajax/Attachments.php
+++ b/tests/phpunit/tests/ajax/Attachments.php
@@ -65,6 +65,8 @@ class Tests_Ajax_Attachments extends WP_Ajax_UnitTestCase {
 	 * @ticket 36578
 	 */
 	public function test_wp_ajax_send_attachment_to_editor_should_return_a_link() {
+		$this->skipWithMultisite();
+
 		// Become an administrator.
 		$post    = $_POST;
 		$user_id = self::factory()->user->create(
diff --git a/tests/phpunit/tests/ajax/DeletePlugin.php b/tests/phpunit/tests/ajax/DeletePlugin.php
index fb2168c339..d84f401a17 100644
--- a/tests/phpunit/tests/ajax/DeletePlugin.php
+++ b/tests/phpunit/tests/ajax/DeletePlugin.php
@@ -126,6 +126,7 @@ class Tests_Ajax_Delete_Plugin extends WP_Ajax_UnitTestCase {
 	}
 
 	public function test_delete_plugin() {
+		$this->skipWithMultisite();
 		$this->_setRole( 'administrator' );
 
 		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
diff --git a/tests/phpunit/tests/ajax/ManageThemes.php b/tests/phpunit/tests/ajax/ManageThemes.php
index 024dd1b6e8..e83a5e7f20 100644
--- a/tests/phpunit/tests/ajax/ManageThemes.php
+++ b/tests/phpunit/tests/ajax/ManageThemes.php
@@ -102,6 +102,7 @@ class Tests_Ajax_Manage_Themes extends WP_Ajax_UnitTestCase {
 	}
 
 	public function test_update_theme() {
+		$this->skipWithMultisite();
 		$this->_setRole( 'administrator' );
 
 		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
@@ -139,6 +140,7 @@ class Tests_Ajax_Manage_Themes extends WP_Ajax_UnitTestCase {
 	}
 
 	function test_uppercase_theme_slug() {
+		$this->skipWithMultisite();
 		$this->_setRole( 'administrator' );
 
 		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
diff --git a/tests/phpunit/tests/ajax/UpdatePlugin.php b/tests/phpunit/tests/ajax/UpdatePlugin.php
index 648164c7b2..ceab32bfeb 100644
--- a/tests/phpunit/tests/ajax/UpdatePlugin.php
+++ b/tests/phpunit/tests/ajax/UpdatePlugin.php
@@ -130,6 +130,7 @@ class Tests_Ajax_Update_Plugin extends WP_Ajax_UnitTestCase {
 	}
 
 	public function test_update_plugin() {
+		$this->skipWithMultisite();
 		$this->_setRole( 'administrator' );
 
 		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );