diff --git a/core/lib/Drupal/Core/Extension/ExtensionNameReservedException.php b/core/lib/Drupal/Core/Extension/ExtensionNameReservedException.php
new file mode 100644
index 0000000000..42569dd627
--- /dev/null
+++ b/core/lib/Drupal/Core/Extension/ExtensionNameReservedException.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace Drupal\Core\Extension;
+
+/**
+ * Exception thrown when the extension's name is already reserved.
+ */
+class ExtensionNameReservedException extends \Exception {}
diff --git a/core/lib/Drupal/Core/Extension/ModuleInstaller.php b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
index bb55a1d852..5a290a9d1f 100644
--- a/core/lib/Drupal/Core/Extension/ModuleInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ModuleInstaller.php
@@ -187,6 +187,12 @@ public function install(array $module_list, $enable_dependencies = TRUE) {
           throw new ExtensionNameLengthException("Module name '$module' is over the maximum allowed length of " . DRUPAL_EXTENSION_NAME_MAX_LENGTH . ' characters');
         }
 
+        // Throw an exception if a theme with the same name is enabled.
+        $installed_themes = $extension_config->get('theme') ?: [];
+        if (isset($installed_themes[$module])) {
+          throw new ExtensionNameReservedException("Module name $module is already in use by an enabled theme.");
+        }
+
         // Load a new config object for each iteration, otherwise changes made
         // in hook_install() are not reflected in $extension_config.
         $extension_config = \Drupal::configFactory()->getEditable('core.extension');
diff --git a/core/lib/Drupal/Core/Extension/ThemeInstaller.php b/core/lib/Drupal/Core/Extension/ThemeInstaller.php
index d377627243..e7246bb19a 100644
--- a/core/lib/Drupal/Core/Extension/ThemeInstaller.php
+++ b/core/lib/Drupal/Core/Extension/ThemeInstaller.php
@@ -207,6 +207,12 @@ public function install(array $theme_list, $install_dependencies = TRUE) {
         throw new ExtensionNameLengthException("Theme name $key is over the maximum allowed length of " . DRUPAL_EXTENSION_NAME_MAX_LENGTH . ' characters.');
       }
 
+      // Throw an exception if a module with the same name is enabled.
+      $installed_modules = $extension_config->get('module') ?: [];
+      if (isset($installed_modules[$key])) {
+        throw new ExtensionNameReservedException("Theme name $key is already in use by an enabled module.");
+      }
+
       // Validate default configuration of the theme. If there is existing
       // configuration then stop installing.
       $this->configInstaller->checkConfigurationToInstall('theme', $key);
diff --git a/core/modules/system/tests/modules/test_theme_module_name_collision/test_theme_module_name_collision.info.yml b/core/modules/system/tests/modules/test_theme_module_name_collision/test_theme_module_name_collision.info.yml
new file mode 100644
index 0000000000..87594d69be
--- /dev/null
+++ b/core/modules/system/tests/modules/test_theme_module_name_collision/test_theme_module_name_collision.info.yml
@@ -0,0 +1,5 @@
+name: 'Same Name'
+type: module
+description: 'Test module with same name as a theme.'
+package: Testing
+version: VERSION
diff --git a/core/modules/system/tests/src/Functional/Module/InstallTest.php b/core/modules/system/tests/src/Functional/Module/InstallTest.php
index 0bc323ea29..77297ac9fe 100644
--- a/core/modules/system/tests/src/Functional/Module/InstallTest.php
+++ b/core/modules/system/tests/src/Functional/Module/InstallTest.php
@@ -99,4 +99,22 @@ public function testModuleNameLength() {
     }
   }
 
+  /**
+   * Tests installing a module with same name as enabled theme.
+   */
+  public function testInstallModuleSameNameAsTheme() {
+    $name = 'test_theme_module_name_collision';
+
+    // Install and uninstall the module.
+    $this->container->get('module_installer')->install([$name]);
+    $this->container->get('module_installer')->uninstall([$name]);
+
+    // Install the theme then module.
+    $this->container->get('theme_installer')->install([$name]);
+    $message = "Module name $name is already in use by an enabled theme.";
+    $this->expectException(ExtensionNameReservedException::class);
+    $this->expectExceptionMessage($message);
+    $this->container->get('module_installer')->install([$name]);
+  }
+
 }
diff --git a/core/modules/system/tests/themes/test_theme_module_name_collision/test_theme_module_name_collision.info.yml b/core/modules/system/tests/themes/test_theme_module_name_collision/test_theme_module_name_collision.info.yml
new file mode 100644
index 0000000000..e08568bd28
--- /dev/null
+++ b/core/modules/system/tests/themes/test_theme_module_name_collision/test_theme_module_name_collision.info.yml
@@ -0,0 +1,5 @@
+name: 'Same Name'
+type: theme
+description: 'Test module with same name as a theme.'
+base theme: stable
+version: VERSION
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php b/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
index 5f92213c30..d0582507f4 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\Extension\ExtensionNameLengthException;
+use Drupal\Core\Extension\ExtensionNameReservedException;
 use Drupal\Core\Extension\MissingDependencyException;
 use Drupal\Core\Extension\ModuleUninstallValidatorException;
 use Drupal\Core\Extension\Exception\UnknownExtensionException;
@@ -139,6 +140,24 @@ public function testInstallNameTooLong() {
     }
   }
 
+  /**
+   * Tests installing a theme with same name as enabled module..
+   */
+  public function testInstallThemeSameNameAsModule() {
+    $name = 'test_theme_module_name_collision';
+
+    // Install and uninstall the theme.
+    $this->themeInstaller()->install([$name]);
+    $this->themeInstaller()->uninstall([$name]);
+
+    // Install the module then the theme.
+    $this->moduleInstaller()->install([$name]);
+    $message = "Theme name $name is already in use by an enabled module.";
+    $this->expectException(ExtensionNameReservedException::class);
+    $this->expectExceptionMessage($message);
+    $this->themeInstaller()->install([$name]);
+  }
+
   /**
    * Tests installing a theme with unmet module dependencies.
    *