diff --git a/rosbag2_storage_mcap/src/mcap_storage.cpp b/rosbag2_storage_mcap/src/mcap_storage.cpp
index 962b426427..4fe6895b22 100644
--- a/rosbag2_storage_mcap/src/mcap_storage.cpp
+++ b/rosbag2_storage_mcap/src/mcap_storage.cpp
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include "rcpputils/thread_safety_annotations.hpp"
 #include "rcutils/logging_macros.h"
 #include "rosbag2_storage/metadata_io.hpp"
 #include "rosbag2_storage/ros_helper.hpp"
@@ -40,6 +41,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <mutex>
 #include <optional>
 #include <string>
 #include <unordered_map>
@@ -228,6 +230,7 @@ class ROSBAG2_STORAGE_MCAP_PUBLIC MCAPStorage
 
 private:
   void read_metadata();
+  void write_lock_free(std::shared_ptr<const rosbag2_storage::SerializedBagMessage> msg);
   void open_impl(const std::string & uri, const std::string & preset_profile,
                  rosbag2_storage::storage_interfaces::IOFlag io_flag,
                  const std::string & storage_config_uri);
@@ -244,9 +247,13 @@ class ROSBAG2_STORAGE_MCAP_PUBLIC MCAPStorage
   std::shared_ptr<rosbag2_storage::SerializedBagMessage> next_;
 
   rosbag2_storage::BagMetadata metadata_{};
-  std::unordered_map<std::string, rosbag2_storage::TopicInformation> topics_;
-  std::unordered_map<std::string, mcap::SchemaId> schema_ids_;    // datatype -> schema_id
-  std::unordered_map<std::string, mcap::ChannelId> channel_ids_;  // topic -> channel_id
+  std::mutex mcap_storage_mutex_;
+  std::unordered_map<std::string, rosbag2_storage::TopicInformation> topics_
+    RCPPUTILS_TSA_GUARDED_BY(mcap_storage_mutex_);
+  std::unordered_map<std::string, mcap::SchemaId> schema_ids_
+    RCPPUTILS_TSA_GUARDED_BY(mcap_storage_mutex_);  // datatype -> schema_id
+  std::unordered_map<std::string, mcap::ChannelId> channel_ids_
+    RCPPUTILS_TSA_GUARDED_BY(mcap_storage_mutex_);  // topic -> channel_id
   rosbag2_storage::StorageFilter storage_filter_{};
   mcap::ReadMessageOptions::ReadOrder read_order_ = mcap::ReadMessageOptions::ReadOrder::FileOrder;
 
@@ -733,6 +740,21 @@ uint64_t MCAPStorage::get_minimum_split_file_size() const
 
 /** BaseWriteInterface **/
 void MCAPStorage::write(std::shared_ptr<const rosbag2_storage::SerializedBagMessage> msg)
+{
+  std::lock_guard<std::mutex> lock(mcap_storage_mutex_);
+  write_lock_free(msg);
+}
+
+void MCAPStorage::write(
+  const std::vector<std::shared_ptr<const rosbag2_storage::SerializedBagMessage>> & msgs)
+{
+  std::lock_guard<std::mutex> lock(mcap_storage_mutex_);
+  for (const auto & msg : msgs) {
+    write_lock_free(msg);
+  }
+}
+
+void MCAPStorage::write_lock_free(std::shared_ptr<const rosbag2_storage::SerializedBagMessage> msg)
 {
   const auto topic_it = topics_.find(msg->topic_name);
   if (topic_it == topics_.end()) {
@@ -773,17 +795,10 @@ void MCAPStorage::write(std::shared_ptr<const rosbag2_storage::SerializedBagMess
   metadata_.duration = std::max(metadata_.duration, message_time - metadata_.starting_time);
 }
 
-void MCAPStorage::write(
-  const std::vector<std::shared_ptr<const rosbag2_storage::SerializedBagMessage>> & msgs)
-{
-  for (const auto & msg : msgs) {
-    write(msg);
-  }
-}
-
 void MCAPStorage::create_topic(const rosbag2_storage::TopicMetadata & topic,
                                const rosbag2_storage::MessageDefinition & message_definition)
 {
+  std::lock_guard<std::mutex> lock(mcap_storage_mutex_);
   auto topic_info = rosbag2_storage::TopicInformation{topic, 0};
   const auto topic_it = topics_.find(topic.name);
   if (topic_it == topics_.end()) {
@@ -830,6 +845,7 @@ void MCAPStorage::create_topic(const rosbag2_storage::TopicMetadata & topic,
 
 void MCAPStorage::remove_topic(const rosbag2_storage::TopicMetadata & topic)
 {
+  std::lock_guard<std::mutex> lock(mcap_storage_mutex_);
   const auto topic_it = topics_.find(topic.name);
   if (topic_it != topics_.end()) {
     const auto & datatype = topic_it->second.topic_metadata.type;