diff --git a/apps/ui/templates/dashboard.html b/apps/ui/templates/dashboard.html
index e3832d4..7ed877a 100644
--- a/apps/ui/templates/dashboard.html
+++ b/apps/ui/templates/dashboard.html
@@ -1661,7 +1661,8 @@
                                    value="50" 
                                    class="brightness-slider"
                                    id="slider-group-${group.id}"
-                                   oninput="updateGroupBrightnessDisplay('${group.id}', this.value)">
+                                   oninput="updateGroupBrightnessDisplay('${group.id}', this.value)"
+                                   onchange="setGroupBrightness('${group.id}', this.value)">
                         </div>
                         ` : ''}
                         <div class="group-card-actions">
@@ -1692,6 +1693,46 @@
             }
         }
         
+        // Set group brightness immediately when slider changes
+        async function setGroupBrightness(groupId, brightness) {
+            try {
+                const response = await fetch(api(`/groups/${groupId}/set`), {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({
+                        action: {
+                            type: 'power',
+                            payload: {
+                                power: 'on',
+                                brightness: parseInt(brightness)
+                            }
+                        }
+                    })
+                });
+                
+                if (!response.ok) {
+                    const error = await response.json();
+                    throw new Error(error.detail || 'Request failed');
+                }
+                
+                const result = await response.json();
+                const publishedCount = result.execution_plan.filter(p => p.status === 'published').length;
+                
+                console.log(`Group ${groupId} brightness set to ${brightness}%: ${publishedCount} devices`);
+                
+                addEvent({
+                    action: 'group_brightness',
+                    group_id: groupId,
+                    brightness: brightness,
+                    device_count: publishedCount
+                });
+                
+            } catch (error) {
+                console.error('Failed to set group brightness:', error);
+                showToast(`Fehler beim Setzen der Helligkeit: ${error.message}`, 'error');
+            }
+        }
+        
         // Execute group action
         async function setGroup(groupId, power, buttonElement) {
             const allButtons = buttonElement.parentElement.querySelectorAll('button');