diff --git a/doc/ot_api_doc.h b/doc/ot_api_doc.h
index f0762eb0c..b231833e2 100644
--- a/doc/ot_api_doc.h
+++ b/doc/ot_api_doc.h
@@ -59,7 +59,16 @@
  * @defgroup api-ip6                  IPv6
  * @defgroup api-srp                  SRP
  * @defgroup api-ping-sender          Ping Sender
+ *
+ * @defgroup api-tcp-group            TCP
+ *
+ * @{
+ *
  * @defgroup api-tcp                  TCP
+ * @defgroup api-tcp-ext              TCP Abstractions
+ *
+ * @}
+ *
  * @defgroup api-udp-group            UDP
  *
  * @{