diff --git a/Lib/asyncio/sslproto.py b/Lib/asyncio/sslproto.py
index cad25b26539f5aa..24e9bb32022f4cd 100644
--- a/Lib/asyncio/sslproto.py
+++ b/Lib/asyncio/sslproto.py
@@ -283,6 +283,7 @@ def feed_appdata(self, data, offset=0):
 class _SSLProtocolTransport(transports._FlowControlMixin,
                             transports.Transport):
 
+    _start_tls_compatible = True
     _sendfile_compatible = constants._SendfileMode.FALLBACK
 
     def __init__(self, loop, ssl_protocol):
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-06-11-04-34-41.bpo-37179.7Gs2-B.rst b/Misc/NEWS.d/next/Core and Builtins/2021-06-11-04-34-41.bpo-37179.7Gs2-B.rst
new file mode 100644
index 000000000000000..62136b816d010b0
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-06-11-04-34-41.bpo-37179.7Gs2-B.rst	
@@ -0,0 +1 @@
+Allow asyncio StartTLS in an existing TLS connection.
\ No newline at end of file