diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 7f9236fd40..0437a2a8a9 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1175,35 +1175,6 @@ function template_preprocess_item_list(&$variables) {
   }
 }
 
-/**
- * Prepares variables for inclusion in a splitbutton item list.
- *
- * @param array $variables
- *   An associative array containing:
- *   - items: An array of items to be displayed in the list.
- *   - list_type: The type of list to return (e.g. "ul", "ol").
- *   - wrapper_attributes: HTML attributes to be applied to the list wrapper.
- */
-function template_preprocess_splitbutton_item_list(array &$variables) {
-  $variables['wrapper_attributes'] = new Attribute($variables['wrapper_attributes']);
-  foreach ($variables['items'] as &$item) {
-    $attributes = [];
-    // If the item value is an array, then it is a render array.
-    if (is_array($item)) {
-      // List items support attributes via the '#wrapper_attributes' property.
-      if (isset($item['#wrapper_attributes'])) {
-        $attributes = $item['#wrapper_attributes'];
-      }
-    }
-
-    // Set the item's value and attributes for the template.
-    $item = [
-      'value' => $item,
-      'attributes' => new Attribute($attributes),
-    ];
-  }
-}
-
 /**
  * Prepares variables for splitbutton templates.
  *
@@ -2102,14 +2073,6 @@ function drupal_common_theme() {
     'item_list' => [
       'variables' => ['items' => [], 'title' => '', 'list_type' => 'ul', 'wrapper_attributes' => [], 'attributes' => [], 'empty' => NULL, 'context' => []],
     ],
-    'splitbutton_item_list' => [
-      'variables' => [
-        'items' => [],
-        'list_type' => 'ul',
-        'wrapper_attributes' => [],
-        'attributes' => [],
-      ],
-    ],
     'splitbutton' => [
       'variables' => [
         'splitbutton_multiple' => TRUE,
diff --git a/core/lib/Drupal/Core/Render/Element/Splitbutton.php b/core/lib/Drupal/Core/Render/Element/Splitbutton.php
index 226344187a..d402289d00 100644
--- a/core/lib/Drupal/Core/Render/Element/Splitbutton.php
+++ b/core/lib/Drupal/Core/Render/Element/Splitbutton.php
@@ -178,9 +178,10 @@ public static function buildItemList(array &$element, array $items) {
       $item['#wrapper_attributes']['role'] = 'none';
     }
 
+
     $element['#splitbutton_item_list'] = [
       '#items' => $items,
-      '#theme' => 'splitbutton_item_list',
+      '#theme' => 'item_list__splitbutton',
       '#attributes' => [
         'data-drupal-splitbutton-target' => $trigger_id,
         'role' => 'menu',
diff --git a/core/misc/splitbutton/splitbutton.css b/core/misc/splitbutton/splitbutton.css
index f12706d860..5b8070d14f 100644
--- a/core/misc/splitbutton/splitbutton.css
+++ b/core/misc/splitbutton/splitbutton.css
@@ -4,6 +4,7 @@
 }
 .js [data-drupal-splitbutton-item-list] {
   display: none;
+  list-style: none;
 }
 [data-drupal-splitbutton-open] [data-drupal-splitbutton-item-list] {
   z-index: 4;
diff --git a/core/misc/splitbutton/splitbutton.es6.js b/core/misc/splitbutton/splitbutton.es6.js
index 1a7aa60912..6467278b50 100644
--- a/core/misc/splitbutton/splitbutton.es6.js
+++ b/core/misc/splitbutton/splitbutton.es6.js
@@ -40,6 +40,14 @@
       this.splitbutton.addEventListener('focusout', () => this.focusOut());
       this.splitbutton.addEventListener('keydown', e => this.keydown(e));
       this.trigger.addEventListener('click', e => this.clickToggle(e));
+
+      // The splitbutton items use the item-list template, but should not be
+      // styled as an item list. Removing the class here addresses this for any
+      // theme displaying a splitbutton.
+      const itemList = splitbutton.querySelector('.item-list');
+      if (itemList) {
+        itemList.classList.remove('item-list');
+      }
     }
 
     /**
diff --git a/core/misc/splitbutton/splitbutton.js b/core/misc/splitbutton/splitbutton.js
index a854337937..56d651c2f0 100644
--- a/core/misc/splitbutton/splitbutton.js
+++ b/core/misc/splitbutton/splitbutton.js
@@ -57,6 +57,11 @@ function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _d
       this.trigger.addEventListener('click', function (e) {
         return _this.clickToggle(e);
       });
+      var itemList = splitbutton.querySelector('.item-list');
+
+      if (itemList) {
+        itemList.classList.remove('item-list');
+      }
     }
 
     _createClass(_class, [{
diff --git a/core/modules/system/templates/splitbutton-item-list.html.twig b/core/modules/system/templates/splitbutton-item-list.html.twig
deleted file mode 100644
index 40483e1359..0000000000
--- a/core/modules/system/templates/splitbutton-item-list.html.twig
+++ /dev/null
@@ -1,24 +0,0 @@
-{#
-/**
- * @file
- * Default theme implementation for a splitbutton item list.
- *
- * Available variables:
- * - items: A list of items. Each item contains:
- *   - attributes: HTML attributes to be applied to each list item.
- *   - value: The content of the list element.
- * - list_type: The tag for list element ("ul" or "ol").
- * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
- *
- * @ingroup themeable
- */
-#}
-{% if items %}
-    <{{ list_type }}{{ attributes }}>
-        {%- for item in items -%}
-            <li{{ item.attributes }}>{{ item.value }}</li>
-        {%- endfor -%}
-    </{{ list_type }}>
-{%- endif %}
diff --git a/core/modules/system/tests/modules/splitbutton_test/src/Element/SplitTextField.php b/core/modules/system/tests/modules/splitbutton_test/src/Element/SplitTextField.php
index 7865d60efd..ece6f9e153 100644
--- a/core/modules/system/tests/modules/splitbutton_test/src/Element/SplitTextField.php
+++ b/core/modules/system/tests/modules/splitbutton_test/src/Element/SplitTextField.php
@@ -87,7 +87,7 @@ public static function buildItemList(&$element, $items) {
 
     $element['#splitbutton_item_list'] = [
       '#items' => $items,
-      '#theme' => 'splitbutton_item_list',
+      '#theme' => 'item_list',
       '#attributes' => [
         'data-drupal-splitbutton-target' => $trigger_id,
         'data-drupal-item-tags' => 'li',
diff --git a/core/themes/bartik/templates/splitbutton-item-list.html.twig b/core/profiles/demo_umami/themes/umami/templates/components/form/item-list--splitbutton.html.twig
similarity index 84%
rename from core/themes/bartik/templates/splitbutton-item-list.html.twig
rename to core/profiles/demo_umami/themes/umami/templates/components/form/item-list--splitbutton.html.twig
index 83d21f9f8a..235e88d8b7 100644
--- a/core/themes/bartik/templates/splitbutton-item-list.html.twig
+++ b/core/profiles/demo_umami/themes/umami/templates/components/form/item-list--splitbutton.html.twig
@@ -1,7 +1,7 @@
 {#
 /**
  * @file
- * Theme override for a splitbutton item list.
+ * Theme override for an item list used by splitbuttons.
  *
  * Available variables:
  * - items: A list of items. Each item contains:
@@ -9,8 +9,6 @@
  *   - value: The content of the list element.
  * - list_type: The tag for list element ("ul" or "ol").
  * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
  */
 #}
 {% if items %}
diff --git a/core/themes/seven/templates/splitbutton-item-list.html.twig b/core/themes/bartik/templates/item-list--splitbutton.html.twig
similarity index 84%
rename from core/themes/seven/templates/splitbutton-item-list.html.twig
rename to core/themes/bartik/templates/item-list--splitbutton.html.twig
index 83d21f9f8a..235e88d8b7 100644
--- a/core/themes/seven/templates/splitbutton-item-list.html.twig
+++ b/core/themes/bartik/templates/item-list--splitbutton.html.twig
@@ -1,7 +1,7 @@
 {#
 /**
  * @file
- * Theme override for a splitbutton item list.
+ * Theme override for an item list used by splitbuttons.
  *
  * Available variables:
  * - items: A list of items. Each item contains:
@@ -9,8 +9,6 @@
  *   - value: The content of the list element.
  * - list_type: The tag for list element ("ul" or "ol").
  * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
  */
 #}
 {% if items %}
diff --git a/core/profiles/demo_umami/themes/umami/templates/components/form/splitbutton-item-list.html.twig b/core/themes/claro/templates/form/item-list--splitbutton.html.twig
similarity index 84%
rename from core/profiles/demo_umami/themes/umami/templates/components/form/splitbutton-item-list.html.twig
rename to core/themes/claro/templates/form/item-list--splitbutton.html.twig
index 83d21f9f8a..235e88d8b7 100644
--- a/core/profiles/demo_umami/themes/umami/templates/components/form/splitbutton-item-list.html.twig
+++ b/core/themes/claro/templates/form/item-list--splitbutton.html.twig
@@ -1,7 +1,7 @@
 {#
 /**
  * @file
- * Theme override for a splitbutton item list.
+ * Theme override for an item list used by splitbuttons.
  *
  * Available variables:
  * - items: A list of items. Each item contains:
@@ -9,8 +9,6 @@
  *   - value: The content of the list element.
  * - list_type: The tag for list element ("ul" or "ol").
  * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
  */
 #}
 {% if items %}
diff --git a/core/themes/claro/templates/form/splitbutton-item-list.html.twig b/core/themes/seven/templates/item-list--splitbutton.html.twig
similarity index 84%
rename from core/themes/claro/templates/form/splitbutton-item-list.html.twig
rename to core/themes/seven/templates/item-list--splitbutton.html.twig
index 83d21f9f8a..235e88d8b7 100644
--- a/core/themes/claro/templates/form/splitbutton-item-list.html.twig
+++ b/core/themes/seven/templates/item-list--splitbutton.html.twig
@@ -1,7 +1,7 @@
 {#
 /**
  * @file
- * Theme override for a splitbutton item list.
+ * Theme override for an item list used by splitbuttons.
  *
  * Available variables:
  * - items: A list of items. Each item contains:
@@ -9,8 +9,6 @@
  *   - value: The content of the list element.
  * - list_type: The tag for list element ("ul" or "ol").
  * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
  */
 #}
 {% if items %}
diff --git a/core/themes/stable/templates/misc/splitbutton-item-list.html.twig b/core/themes/stable/templates/misc/splitbutton-item-list.html.twig
deleted file mode 100644
index 3f66836428..0000000000
--- a/core/themes/stable/templates/misc/splitbutton-item-list.html.twig
+++ /dev/null
@@ -1,22 +0,0 @@
-{#
-/**
- * @file
- * Theme override for a splitbutton item list.
- *
- * Available variables:
- * - items: A list of items. Each item contains:
- *   - attributes: HTML attributes to be applied to each list item.
- *   - value: The content of the list element.
- * - list_type: The tag for list element ("ul" or "ol").
- * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
- */
-#}
-{% if items %}
-    <{{ list_type }}{{ attributes }}>
-        {%- for item in items -%}
-            <li{{ item.attributes }}>{{ item.value }}</li>
-        {%- endfor -%}
-    </{{ list_type }}>
-{%- endif %}
diff --git a/core/themes/stable9/templates/misc/splitbutton-item-list.html.twig b/core/themes/stable9/templates/misc/splitbutton-item-list.html.twig
deleted file mode 100644
index 3f66836428..0000000000
--- a/core/themes/stable9/templates/misc/splitbutton-item-list.html.twig
+++ /dev/null
@@ -1,22 +0,0 @@
-{#
-/**
- * @file
- * Theme override for a splitbutton item list.
- *
- * Available variables:
- * - items: A list of items. Each item contains:
- *   - attributes: HTML attributes to be applied to each list item.
- *   - value: The content of the list element.
- * - list_type: The tag for list element ("ul" or "ol").
- * - attributes: HTML attributes to be applied to the list.
- *
- * @see template_preprocess_splitbutton_item_list()
- */
-#}
-{% if items %}
-    <{{ list_type }}{{ attributes }}>
-        {%- for item in items -%}
-            <li{{ item.attributes }}>{{ item.value }}</li>
-        {%- endfor -%}
-    </{{ list_type }}>
-{%- endif %}