diff --git a/Firestore/src/Connection/Grpc.php b/Firestore/src/Connection/Grpc.php
index e9a1218c2163..037ee6a7b96f 100644
--- a/Firestore/src/Connection/Grpc.php
+++ b/Firestore/src/Connection/Grpc.php
@@ -56,6 +56,11 @@ class Grpc implements ConnectionInterface
      */
     private $resourcePrefixHeader;
 
+    /**
+     * @var string
+     */
+    private $databaseRoutingHeader;
+
     /**
      * @var bool
      */
@@ -113,10 +118,17 @@ public function __construct(array $config = [])
         //@codeCoverageIgnoreEnd
 
         $this->firestore = $this->constructGapic(FirestoreClient::class, $grpcConfig);
+        $projectId = $this->pluck('projectId', $config);
+        $databaseId = $this->pluck('database', $config);
 
         $this->resourcePrefixHeader = FirestoreClient::databaseRootName(
-            $this->pluck('projectId', $config),
-            $this->pluck('database', $config)
+            $projectId,
+            $databaseId
+        );
+        $this->databaseRoutingHeader = sprintf(
+            'project_id=%s&database_id=%s',
+            $projectId,
+            $databaseId
         );
     }
 
@@ -301,6 +313,7 @@ private function addRequestHeaders(array $args)
         ];
 
         $args['headers']['google-cloud-resource-prefix'] = [$this->resourcePrefixHeader];
+        $args['headers']['x-goog-request-params'] = [$this->databaseRoutingHeader];
 
         // Provide authentication header for requests when emulator is enabled.
         if ($this->isUsingEmulator) {
@@ -339,6 +352,7 @@ public function __debugInfo()
             'serializer' => get_class($this->serializer),
             'firestore' => get_class($this->firestore),
             'resourcePrefixHeader' => $this->resourcePrefixHeader,
+            'databaseRoutingHeader' => $this->databaseRoutingHeader,
             'isUsingEmulator' => $this->isUsingEmulator
         ];
     }
diff --git a/Firestore/tests/System/FirestoreMultipleDbTest.php b/Firestore/tests/System/FirestoreMultipleDbTest.php
new file mode 100644
index 000000000000..56f6d6aaac33
--- /dev/null
+++ b/Firestore/tests/System/FirestoreMultipleDbTest.php
@@ -0,0 +1,119 @@
+<?php
+/**
+ * Copyright 2023 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+namespace Google\Cloud\Firestore\Tests\System;
+
+use Google\Cloud\Firestore\FieldPath;
+use Google\Cloud\Firestore\Query;
+
+/**
+ * @group firestore
+ * @group firestore-multipledb
+ */
+class FirestoreMultipleDbTest extends FirestoreTestCase
+{
+    private $document;
+
+    public function setUp(): void
+    {
+        $this->document = self::$multiDbCollection->newDocument();
+    }
+
+    public function testInsert()
+    {
+        $this->assertFalse($this->document->snapshot()->exists());
+
+        self::$multiDbClient->runTransaction(function ($t) {
+            $t->create($this->document, [
+                'foo' => 'bar'
+            ]);
+        });
+
+        $this->assertTrue($this->document->snapshot()->exists());
+    }
+
+    public function testUpdate()
+    {
+        $this->document->create([
+            'foo' => 'bar'
+        ]);
+
+        self::$multiDbClient->runTransaction(function ($t) {
+            $t->update($this->document, [
+                ['path' => 'bat', 'value' => 'baz']
+            ]);
+        });
+
+        $this->assertEquals([
+            'foo' => 'bar',
+            'bat' => 'baz'
+        ], $this->document->snapshot()->data());
+    }
+
+
+    public function testCollectionGroup()
+    {
+        // Create a random collection name, but make sure
+        // it starts with 'b' for predictable ordering.
+        $collectionGroup = 'b' . uniqid(self::COLLECTION_NAME);
+        $query = $this->createDocuments([
+            // following doc paths will match based on the collection group id
+            'abc/123/%s/cg-doc1',
+            'abc/123/%s/cg-doc2',
+            '%s/cg-doc3',
+            '%s/cg-doc4',
+            'def/456/%s/cg-doc5',
+            // following doc paths will NOT match with collection group id
+            '%s/virtual-doc/nested-coll/not-cg-doc', // nested-coll
+            'x%s/not-cg-doc',                        // x-prefix
+            '%sx/not-cg-doc',                        // x-suffix
+            'abc/123/%sx/not-cg-doc',                // x-prefix
+            'abc/123/x%s/not-cg-doc',                // x-suffix
+            'abc/%s',                                // abc
+        ], $collectionGroup);
+
+        $query = self::$multiDbClient->collectionGroup($collectionGroup);
+        $documentIds = array_map(
+            fn($doc) => $doc->id(),
+            // Returns docs only with matching exact collection group id
+            $query->documents()->rows()
+        );
+        $this->assertEqualsCanonicalizing(
+            ['cg-doc1', 'cg-doc2', 'cg-doc3', 'cg-doc4', 'cg-doc5'],
+            $documentIds
+        );
+    }
+
+    private function createDocuments(array $paths, $collectionGroupId)
+    {
+        foreach ($paths as &$path) {
+            $path = sprintf($path, $collectionGroupId);
+        }
+        $batch = self::$multiDbClient->bulkWriter();
+
+        foreach ($paths as $docpath) {
+            $doc = self::$multiDbClient->document($docpath);
+            self::$localDeletionQueue->add($doc);
+            $batch->set($doc, [
+                'x' => 1
+            ]);
+        }
+
+        $batch->flush();
+        self::$localDeletionQueue->add($collectionGroupId);
+    }
+}
diff --git a/Firestore/tests/System/FirestoreTestCase.php b/Firestore/tests/System/FirestoreTestCase.php
index 949c7c91e5ea..770ea2e8bbb5 100644
--- a/Firestore/tests/System/FirestoreTestCase.php
+++ b/Firestore/tests/System/FirestoreTestCase.php
@@ -25,9 +25,12 @@
 class FirestoreTestCase extends SystemTestCase
 {
     const COLLECTION_NAME = 'system-test';
+    const TEST_DB_NAME = 'system-tests-named-db';
 
     protected static $client;
+    protected static $multiDbClient;
     protected static $collection;
+    protected static $multiDbCollection;
     protected static $localDeletionQueue;
     private static $hasSetUp = false;
 
@@ -43,9 +46,14 @@ public static function setUpBeforeClass(): void
         self::$client = new FirestoreClient([
             'keyFilePath' => $keyFilePath
         ]);
+        self::$multiDbClient = new FirestoreClient([
+            'keyFilePath' => $keyFilePath,
+            'database' => self::TEST_DB_NAME
+        ]);
         self::$collection = self::$client->collection(uniqid(self::COLLECTION_NAME));
+        self::$multiDbCollection = self::$multiDbClient->collection(uniqid(self::COLLECTION_NAME));
         self::$localDeletionQueue->add(self::$collection);
-
+        self::$localDeletionQueue->add(self::$multiDbCollection);
 
         self::$hasSetUp = true;
     }
diff --git a/Firestore/tests/Unit/Connection/GrpcTest.php b/Firestore/tests/Unit/Connection/GrpcTest.php
index 9f982162d908..a05499f7981b 100644
--- a/Firestore/tests/Unit/Connection/GrpcTest.php
+++ b/Firestore/tests/Unit/Connection/GrpcTest.php
@@ -404,7 +404,8 @@ private function header()
     {
         return [
             "headers" => [
-                "google-cloud-resource-prefix" => ["projects/test/databases/(default)"]
+                "google-cloud-resource-prefix" => ["projects/test/databases/(default)"],
+                "x-goog-request-params" => ["project_id=test&database_id=(default)"]
             ]
         ];
     }