diff --git a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/runtime/DeploymentExecutor.java b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/runtime/DeploymentExecutor.java
index f56e91aa..c35bbb60 100644
--- a/cameleer3-server-app/src/main/java/com/cameleer3/server/app/runtime/DeploymentExecutor.java
+++ b/cameleer3-server-app/src/main/java/com/cameleer3/server/app/runtime/DeploymentExecutor.java
@@ -147,6 +147,16 @@ public class DeploymentExecutor {
                 additionalNets.add(envNet);
             }
 
+            // User-configured extra networks (e.g., monitoring)
+            if (networkManager != null && config.extraNetworks() != null) {
+                for (String net : config.extraNetworks()) {
+                    if (!net.isBlank() && !additionalNets.contains(net)) {
+                        networkManager.ensureNetwork(net);
+                        additionalNets.add(net);
+                    }
+                }
+            }
+
             // === START REPLICAS ===
             updateStage(deployment.id(), DeployStage.START_REPLICAS);
 
@@ -370,6 +380,7 @@ public class DeploymentExecutor {
         map.put("deploymentStrategy", config.deploymentStrategy());
         map.put("runtimeType", config.runtimeType());
         map.put("customArgs", config.customArgs());
+        map.put("extraNetworks", config.extraNetworks());
         return map;
     }
 }
diff --git a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ConfigMerger.java b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ConfigMerger.java
index cf7aa7d0..edd8b7b3 100644
--- a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ConfigMerger.java
+++ b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ConfigMerger.java
@@ -32,7 +32,8 @@ public final class ConfigMerger {
                 boolVal(appConfig, envConfig, "routeControlEnabled", true),
                 boolVal(appConfig, envConfig, "replayEnabled", true),
                 stringVal(appConfig, envConfig, "runtimeType", "auto"),
-                stringVal(appConfig, envConfig, "customArgs", "")
+                stringVal(appConfig, envConfig, "customArgs", ""),
+                stringList(appConfig, envConfig, "extraNetworks")
         );
     }
 
@@ -78,6 +79,17 @@ public final class ConfigMerger {
         return List.of();
     }
 
+    private static List<String> stringList(Map<String, Object> app, Map<String, Object> env, String key) {
+        Object val = app.containsKey(key) ? app.get(key) : env.get(key);
+        if (val instanceof List<?> list) {
+            return list.stream()
+                    .filter(String.class::isInstance)
+                    .map(String.class::cast)
+                    .toList();
+        }
+        return List.of();
+    }
+
     @SuppressWarnings("unchecked")
     private static Map<String, String> stringMap(Map<String, Object> app, Map<String, Object> env, String key) {
         Object val = app.containsKey(key) ? app.get(key) : env.get(key);
diff --git a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ResolvedContainerConfig.java b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ResolvedContainerConfig.java
index 8d174951..b1674745 100644
--- a/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ResolvedContainerConfig.java
+++ b/cameleer3-server-core/src/main/java/com/cameleer3/server/core/runtime/ResolvedContainerConfig.java
@@ -21,7 +21,8 @@ public record ResolvedContainerConfig(
         boolean routeControlEnabled,
         boolean replayEnabled,
         String runtimeType,
-        String customArgs
+        String customArgs,
+        List<String> extraNetworks
 ) {
     public long memoryLimitBytes() {
         return (long) memoryLimitMb * 1024 * 1024;
diff --git a/ui/src/pages/AppsTab/AppsTab.tsx b/ui/src/pages/AppsTab/AppsTab.tsx
index da9d08e2..004cd8d1 100644
--- a/ui/src/pages/AppsTab/AppsTab.tsx
+++ b/ui/src/pages/AppsTab/AppsTab.tsx
@@ -211,6 +211,8 @@ function CreateAppView({ environments, selectedEnv }: { environments: Environmen
   const [sslOffloading, setSslOffloading] = useState(true);
   const [runtimeType, setRuntimeType] = useState(String(defaults.runtimeType ?? 'auto'));
   const [customArgs, setCustomArgs] = useState(String(defaults.customArgs ?? ''));
+  const [extraNetworks, setExtraNetworks] = useState<string[]>(Array.isArray(defaults.extraNetworks) ? defaults.extraNetworks as string[] : []);
+  const [newNetwork, setNewNetwork] = useState('');
 
   const [configTab, setConfigTab] = useState<'monitoring' | 'resources' | 'variables'>('monitoring');
   const [busy, setBusy] = useState(false);
@@ -226,6 +228,7 @@ function CreateAppView({ environments, selectedEnv }: { environments: Environmen
     setPorts(Array.isArray(d.exposedPorts) ? d.exposedPorts as number[] : []);
     setRuntimeType(String(d.runtimeType ?? 'auto'));
     setCustomArgs(String(d.customArgs ?? ''));
+    setExtraNetworks(Array.isArray(d.extraNetworks) ? d.extraNetworks as string[] : []);
   }, [envId, environments]);
 
   useEffect(() => {
@@ -267,6 +270,7 @@ function CreateAppView({ environments, selectedEnv }: { environments: Environmen
         sslOffloading: sslOffloading,
         runtimeType: runtimeType,
         customArgs: customArgs || null,
+        extraNetworks: extraNetworks,
       };
       await updateContainerConfig.mutateAsync({ appId: app.slug, config: containerConfig });
 
@@ -500,6 +504,23 @@ function CreateAppView({ environments, selectedEnv }: { environments: Environmen
               <Toggle checked={sslOffloading} onChange={() => !busy && setSslOffloading(!sslOffloading)} disabled={busy} />
               <span className={sslOffloading ? styles.toggleEnabled : styles.toggleDisabled}>{sslOffloading ? 'Enabled' : 'Disabled'}</span>
             </div>
+
+            <span className={styles.configLabel}>Extra Networks</span>
+            <div>
+              <div className={styles.portPills}>
+                {extraNetworks.map((n) => (
+                  <span key={n} className={styles.portPill}>
+                    {n}
+                    <button className={styles.portPillDelete} disabled={busy}
+                      onClick={() => !busy && setExtraNetworks(extraNetworks.filter((x) => x !== n))}>&times;</button>
+                  </span>
+                ))}
+                <input className={styles.portAddInput} disabled={busy} placeholder="+ network" value={newNetwork}
+                  onChange={(e) => setNewNetwork(e.target.value)}
+                  onKeyDown={(e) => { if (e.key === 'Enter') { e.preventDefault(); const v = newNetwork.trim(); if (v && !extraNetworks.includes(v)) { setExtraNetworks([...extraNetworks, v]); setNewNetwork(''); } } }} />
+              </div>
+              <span className={styles.configHint}>Additional Docker networks to join (e.g., monitoring, prometheus)</span>
+            </div>
           </div>
         </div>
       )}
@@ -829,6 +850,8 @@ function ConfigSubTab({ app, environment }: { app: App; environment?: Environmen
   const [sslOffloading, setSslOffloading] = useState(true);
   const [runtimeType, setRuntimeType] = useState(String(merged.runtimeType ?? 'auto'));
   const [customArgs, setCustomArgs] = useState(String(merged.customArgs ?? ''));
+  const [extraNetworks, setExtraNetworks] = useState<string[]>(Array.isArray(merged.extraNetworks) ? merged.extraNetworks as string[] : []);
+  const [newNetwork, setNewNetwork] = useState('');
 
   // Versions query for runtime detection hints
   const { data: versions = [] } = useAppVersions(app.slug);
@@ -862,6 +885,7 @@ function ConfigSubTab({ app, environment }: { app: App; environment?: Environmen
     setSslOffloading(merged.sslOffloading !== false);
     setRuntimeType(String(merged.runtimeType ?? 'auto'));
     setCustomArgs(String(merged.customArgs ?? ''));
+    setExtraNetworks(Array.isArray(merged.extraNetworks) ? merged.extraNetworks as string[] : []);
   }, [agentConfig, merged]);
 
   useEffect(() => { syncFromServer(); }, [syncFromServer]);
@@ -913,6 +937,7 @@ function ConfigSubTab({ app, environment }: { app: App; environment?: Environmen
       sslOffloading: sslOffloading,
       runtimeType: runtimeType,
       customArgs: customArgs || null,
+      extraNetworks: extraNetworks,
     };
     try {
       await updateContainerConfig.mutateAsync({ appId: app.slug, config: containerConfig });
@@ -1198,6 +1223,23 @@ function ConfigSubTab({ app, environment }: { app: App; environment?: Environmen
               <Toggle checked={sslOffloading} onChange={() => editing && setSslOffloading(!sslOffloading)} disabled={!editing} />
               <span className={sslOffloading ? styles.toggleEnabled : styles.toggleDisabled}>{sslOffloading ? 'Enabled' : 'Disabled'}</span>
             </div>
+
+            <span className={styles.configLabel}>Extra Networks</span>
+            <div>
+              <div className={styles.portPills}>
+                {extraNetworks.map((n) => (
+                  <span key={n} className={styles.portPill}>
+                    {n}
+                    <button className={styles.portPillDelete} disabled={!editing}
+                      onClick={() => editing && setExtraNetworks(extraNetworks.filter((x) => x !== n))}>&times;</button>
+                  </span>
+                ))}
+                <input className={styles.portAddInput} disabled={!editing} placeholder="+ network" value={newNetwork}
+                  onChange={(e) => setNewNetwork(e.target.value)}
+                  onKeyDown={(e) => { if (e.key === 'Enter') { e.preventDefault(); const v = newNetwork.trim(); if (v && !extraNetworks.includes(v)) { setExtraNetworks([...extraNetworks, v]); setNewNetwork(''); } } }} />
+              </div>
+              <span className={styles.configHint}>Additional Docker networks to join (e.g., monitoring, prometheus)</span>
+            </div>
           </div>
         </div>
       )}