Route 165 is a state highway in southeastern Connecticut running from Norwich to the Rhode Island state line in Voluntown, where it continues as Rhode Island Route 165.

In Preston, it continues east through the town into Griswold.

Between 1932 and 1936, it was rerouted to its current location crossing Pachaug Pond at its southern end.

In 1947, it was extended to the Rhode Island state line.

In 1960, a section in Norwich and Preston was rerouted from Long Society Road to its current location.