diff --git a/composer.json b/composer.json
index 811b624..c1e28df 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,7 @@
     "require": {
         "php": ">=8.1",
         "npm-asset/select2": "^4.0.13",
+        "npm-asset/select2-bootstrap-5-theme": "^1.3.0",
         "yii2-extensions/asset-bootstrap5": "^0.1",
         "yiisoft/yii2": "^2.0.49 || ^2.2"
     },
diff --git a/src/Select2.php b/src/Select2.php
index 57dfc1b..20a57a7 100644
--- a/src/Select2.php
+++ b/src/Select2.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace Yii2\Extension\Select2;
+namespace Yii2\Extensions\Select2;
 
 use yii\helpers\Html;
 use yii\helpers\Json;
@@ -39,7 +39,20 @@ protected function registerPlugin($name)
         Select2Asset::register($view);
         $id = $this->options['id'];
         if ($this->clientOptions !== false) {
-            $options = empty($this->clientOptions) ? '' : Json::encode($this->clientOptions);
+            $options = empty($this->clientOptions) ? [] : $this->clientOptions;
+
+            if (!isset($options['theme'])) {
+                //Do we have BS5?
+                if (class_exists('Yii2\Asset\BootstrapAsset')) {
+                    $view->registerCssFile('@npm/select2-bootstrap-5-theme/dist/select2-bootstrap-5-theme.min.css');
+                    $options['theme'] = 'bootstrap-5';
+                } else {
+                    $options['theme'] = 'classic';
+                }
+            }
+
+            $options = Json::encode($options);
+
             $js = "jQuery('#$id').$name($options);";
             $view->registerJs($js);
         }
diff --git a/src/Select2Asset.php b/src/Select2Asset.php
index c04b851..ffbd48d 100644
--- a/src/Select2Asset.php
+++ b/src/Select2Asset.php
@@ -2,7 +2,7 @@
 
 declare(strict_types=1);
 
-namespace Yii2\Extension\Select2;
+namespace Yii2\Extensions\Select2;
 
 use yii\web\AssetBundle;
 
@@ -21,9 +21,24 @@ class Select2Asset extends AssetBundle
 
     public $depends = [
         'yii\web\JqueryAsset',
-        'yii\bootstrap\BootstrapAsset',
     ];
 
+    public function init()
+    {
+        parent::init();
+
+        //which BS version is installed (from highest to lowest)
+        if (class_exists('yii\bootstrap5\BootstrapAsset')) { //BS5 official
+            $this->depends[] = 'yii\bootstrap5\BootstrapAsset';
+        } else if (class_exists('Yii2\Asset\BootstrapAsset')) { //BS5 Yii2-Ext
+            $this->depends[] = 'Yii2\Asset\BootstrapAsset';
+        } else if (class_exists('yii\bootstrap4\BootstrapAsset')) {
+            $this->depends[] = 'yii\bootstrap4\BootstrapAsset';
+        } else {
+            $this->depends[] = 'yii\bootstrap\BootstrapAsset';
+        }
+    }
+
     /**
      * @inheritdoc
      */