diff --git a/agents/drivers/cassandra/src/main/java/com/dbx/agent/cassandra/CassandraAgent.java b/agents/drivers/cassandra/src/main/java/com/dbx/agent/cassandra/CassandraAgent.java
index 8d68245ab..6ef9f34da 100644
--- a/agents/drivers/cassandra/src/main/java/com/dbx/agent/cassandra/CassandraAgent.java
+++ b/agents/drivers/cassandra/src/main/java/com/dbx/agent/cassandra/CassandraAgent.java
@@ -163,7 +163,13 @@ public final class CassandraAgent extends AbstractJdbcAgent {
         String baseUrl = "jdbc:cassandra://" + params.getHost() + ":" + params.getPort();
         String keyspace = coalesce(params.getDatabase()).trim();
         // Cassandra rejects an empty keyspace path; omit it so DBX can connect first and list keyspaces.
-        return keyspace.isEmpty() ? baseUrl : baseUrl + "/" + keyspace;
+        String url = keyspace.isEmpty() ? baseUrl : baseUrl + "/" + keyspace;
+        // Multi-DC clusters require localdatacenter=<dc>
+        String extraParams = coalesce(params.getUrl_params()).trim();
+        while (extraParams.startsWith("?") || extraParams.startsWith("&")) {
+            extraParams = extraParams.substring(1);
+        }
+        return extraParams.isEmpty() ? url : url + "?" + extraParams;
     }
 
     private static List<String> targetColumns(String options) {
diff --git a/agents/drivers/cassandra/src/test/java/com/dbx/agent/cassandra/CassandraAgentTest.java b/agents/drivers/cassandra/src/test/java/com/dbx/agent/cassandra/CassandraAgentTest.java
index 3dabb472c..4eb9e6be6 100644
--- a/agents/drivers/cassandra/src/test/java/com/dbx/agent/cassandra/CassandraAgentTest.java
+++ b/agents/drivers/cassandra/src/test/java/com/dbx/agent/cassandra/CassandraAgentTest.java
@@ -31,4 +31,22 @@ class CassandraAgentTest extends JdbcFakeExecutionBehaviorTest {
 
         assertEquals("jdbc:cassandra://127.0.0.1:9042/app_keyspace", CassandraAgent.buildUrl(params));
     }
+
+    @Test
+    void appendsUrlParamsForMultiDcLocalDatacenter() {
+        ConnectParams params = new ConnectParams(
+            "127.0.0.1", 9042, "app_keyspace", "cassandra", "cassandra", "localdatacenter=dc1", "", false
+        );
+
+        assertEquals("jdbc:cassandra://127.0.0.1:9042/app_keyspace?localdatacenter=dc1", CassandraAgent.buildUrl(params));
+    }
+
+    @Test
+    void stripsLeadingQuestionMarkFromUrlParams() {
+        ConnectParams params = new ConnectParams(
+            "127.0.0.1", 9042, "", "cassandra", "cassandra", "?localdatacenter=dc1", "", false
+        );
+
+        assertEquals("jdbc:cassandra://127.0.0.1:9042?localdatacenter=dc1", CassandraAgent.buildUrl(params));
+    }
 }
diff --git a/apps/desktop/src/components/connection/ConnectionDialog.vue b/apps/desktop/src/components/connection/ConnectionDialog.vue
index 76f2f3db1..2eff0f04a 100644
--- a/apps/desktop/src/components/connection/ConnectionDialog.vue
+++ b/apps/desktop/src/components/connection/ConnectionDialog.vue
@@ -4575,7 +4575,9 @@ function openExternalUrl(url: string) {
                                   ? 'CLIENT_LOCALE=en_US.utf8;DB_LOCALE=en_US.utf8'
                                   : form.db_type === 'spark'
                                     ? 'catalog=paimon_catalog'
-                                    : 'sslmode=disable'
+                                    : form.db_type === 'cassandra'
+                                      ? 'localdatacenter=dc1'
+                                      : 'sslmode=disable'
                       "
                     />
                   </div>