diff --git a/r2dbc/core/src/main/java/com/google/cloud/sql/core/GcpConnectionFactoryProvider.java b/r2dbc/core/src/main/java/com/google/cloud/sql/core/GcpConnectionFactoryProvider.java
index 6ebd7be35..b0ca22aaa 100644
--- a/r2dbc/core/src/main/java/com/google/cloud/sql/core/GcpConnectionFactoryProvider.java
+++ b/r2dbc/core/src/main/java/com/google/cloud/sql/core/GcpConnectionFactoryProvider.java
@@ -124,11 +124,22 @@ public ConnectionFactory create(ConnectionFactoryOptions connectionFactoryOption
             ? RefreshStrategy.LAZY
             : RefreshStrategy.BACKGROUND;
 
+    final String r2dbcHostname = (String) connectionFactoryOptions.getRequiredValue(HOST);
+    final String cloudSqlInstance;
+    final String domainName;
+    if (CloudSqlInstanceName.isValidInstanceName(r2dbcHostname)) {
+      cloudSqlInstance = r2dbcHostname;
+      domainName = null;
+    } else {
+      cloudSqlInstance = null;
+      domainName = r2dbcHostname;
+    }
+
     Builder optionBuilder = createBuilder(connectionFactoryOptions);
-    String cloudSqlInstance = (String) connectionFactoryOptions.getRequiredValue(HOST);
     ConnectionConfig config =
         new ConnectionConfig.Builder()
             .withCloudSqlInstance(cloudSqlInstance)
+            .withDomainName(domainName)
             .withAuthType(enableIamAuth ? AuthType.IAM : AuthType.PASSWORD)
             .withIpTypes(ipTypes)
             .withNamedConnector(namedConnector)
diff --git a/r2dbc/core/src/test/java/com/google/cloud/sql/core/GcpConnectionFactoryProviderTest.java b/r2dbc/core/src/test/java/com/google/cloud/sql/core/GcpConnectionFactoryProviderTest.java
index b3b63d95f..0f50b5600 100644
--- a/r2dbc/core/src/test/java/com/google/cloud/sql/core/GcpConnectionFactoryProviderTest.java
+++ b/r2dbc/core/src/test/java/com/google/cloud/sql/core/GcpConnectionFactoryProviderTest.java
@@ -18,6 +18,8 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.cloud.sql.AuthType;
+import com.google.cloud.sql.ConnectorConfig;
+import com.google.cloud.sql.ConnectorRegistry;
 import com.google.cloud.sql.IpType;
 import com.google.cloud.sql.RefreshStrategy;
 import io.netty.handler.ssl.SslContextBuilder;
@@ -107,6 +109,26 @@ public void testCreateWithAdminApiOptions() {
     assertThat(config.getConnectorConfig().getAdminServicePath()).isEqualTo("/service");
   }
 
+  @Test
+  public void testCreateWithDomainName() {
+    ConnectorRegistry.register(
+        "resolver-test",
+        new ConnectorConfig.Builder()
+            .withInstanceNameResolver(
+                (n) -> "db.example.com".equals(n) ? "project:region:instance" : null)
+            .build());
+    ConnectionFactoryOptions.Builder options = ConnectionFactoryOptions.builder();
+    options.option(ConnectionFactoryOptions.PROTOCOL, "cloudsql");
+    options.option(ConnectionFactoryOptions.HOST, "db.example.com");
+    options.option(GcpConnectionFactoryProvider.NAMED_CONNECTOR, "resolver-test");
+
+    StubConnectionFactory factory = configureConnection(options.build());
+    ConnectionConfig config = factory.config;
+
+    assertThat(config.getDomainName()).isEqualTo("db.example.com");
+    assertThat(config.getCloudSqlInstance()).isNull();
+  }
+
   private static class StubConnectionFactory implements ConnectionFactory {
 
     final ConnectionConfig config;