diff --git a/block_class.module b/block_class.module
index 7edd4f0..9e90cac 100644
--- a/block_class.module
+++ b/block_class.module
@@ -21,6 +21,22 @@ function block_class_block_presave(BlockInterface $entity) {
   }
 }
 
+function block_class_form_layout_builder_configure_block_alter(&$form, FormStateInterface $form_state, $form_id) {
+  if (\Drupal::currentUser()->hasPermission('administer block classes')) {
+    /** @var \Drupal\layout_builder\SectionComponent $section_component */
+    $section_component = $form_state->getFormObject()->getCurrentComponent();
+    // We need to add the submit before save to ensure TPS to be saved.
+    array_unshift($form['#submit'], 'block_class_form_layout_builder_configure_block_submit');
+
+    $form['settings']['block_class_classes'] = [
+      '#type' => 'textfield',
+      '#title' => t('CSS class(es)'),
+      '#description' => t('Customize the styling of this block by adding CSS classes. Separate multiple classes by spaces.'),
+      '#default_value' => $section_component->getThirdPartySetting('block_class', 'classes'),
+    ];
+  }
+}
+
 /**
  * Implements hook_form_FORM_ID_alter().
  */
@@ -59,6 +75,33 @@ function block_class_preprocess_block(&$variables) {
   }
 }
 
+/**
+ * Implements hook_preprocess_HOOK().
+ */
+function block_class_preprocess_layout(&$variables) {
+  $layout = $variables['layout'] ?? NULL;
+  if ($regions = $layout->getRegionNames()) {
+    foreach ($regions as $region_name) {
+      if (isset($variables['content'][$region_name])) {
+        _block_class_layout_builder_add_classes($variables, $region_name);
+      }
+    }
+  }
+}
+
+/**
+ * Helper function for adding classes via layout builder.
+ */
+function _block_class_layout_builder_add_classes(&$variables, $region_name) {
+  foreach ($variables['content'][$region_name] as &$section_component) {
+    if (is_array($section_component) && isset($section_component['#block_class']['classes'])) {
+      $classes = explode(' ', $section_component['#block_class']['classes']);
+      $existing_classes = $section_component['#attributes']['class'] ?? [];
+      $section_component['#attributes']['class'] = array_merge($existing_classes, $classes);
+    }
+  }
+}
+
 /**
  * Implements hook_help().
  */
@@ -83,3 +126,17 @@ function block_class_help($route_name, RouteMatchInterface $route_match) {
       return $output;
   }
 }
+
+/**
+ * Layout builder configure block submit.
+ */
+function block_class_form_layout_builder_configure_block_submit($form, FormStateInterface $form_state) {
+  /** @var \Drupal\layout_builder\SectionComponent $section_component */
+  $section_component = $form_state->getFormObject()->getCurrentComponent();
+  if ($classes = $form_state->getValue(['settings', 'block_class_classes'])) {
+    $section_component->setThirdPartySetting('block_class', 'classes', $classes);
+  }
+  else {
+    $section_component->unsetThirdPartySetting('block_class', 'classes');
+  }
+}
diff --git a/block_class.services.yml b/block_class.services.yml
new file mode 100644
index 0000000..cbe28b9
--- /dev/null
+++ b/block_class.services.yml
@@ -0,0 +1,6 @@
+services:
+  block_class.render_block_component_subscriber:
+    class: Drupal\block_class\EventSubscriber\BlockComponentRenderArray
+    arguments: []
+    tags:
+      - { name: event_subscriber }
diff --git a/src/EventSubscriber/BlockComponentRenderArray.php b/src/EventSubscriber/BlockComponentRenderArray.php
new file mode 100644
index 0000000..3dcf64f
--- /dev/null
+++ b/src/EventSubscriber/BlockComponentRenderArray.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace Drupal\block_class\EventSubscriber;
+
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+use Drupal\layout_builder\LayoutBuilderEvents;
+use Drupal\layout_builder\Event\SectionComponentBuildRenderArrayEvent;
+
+/**
+ * Class SectionComponentRender.
+ */
+class BlockComponentRenderArray implements EventSubscriberInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    $events[LayoutBuilderEvents::SECTION_COMPONENT_BUILD_RENDER_ARRAY] = ['onBuildRender'];
+    return $events;
+  }
+
+  /**
+   * Adds block classes to section component.
+   *
+   * @param \Drupal\layout_builder\Event\SectionComponentBuildRenderArrayEvent $event
+   *   The section component render event.
+   */
+  public function onBuildRender(SectionComponentBuildRenderArrayEvent $event) {
+    $build = $event->getBuild();
+    if (!empty($build)) {
+      $build['#block_class'] = $event->getComponent()->getThirdPartySettings('block_class');
+      $event->setBuild($build);
+    }
+  }
+
+}