The Rinkai Line (りんかい線, Rinkai-sen^?) is a railway line located in Tokyo, Japan. It is the only line operated by the third-sector company Tokyo Waterfront Area Rapid Transit. It connects central Tokyo to the artificial islands of Aomi and Odaiba. The line is served by some trains on the East Japan Railway Company (JR East) Saikyō Line which continue on to Shinjuku, Ikebukuro, Ōmiya, and Kawagoe.

While usually not considered an official part of the Tokyo subway network, the Rinkai Line runs underground for nearly 10 km of its 12.2 km distance, going as low as 40 meters below the ground when crossing under the Port of Tokyo. Only the Shinonome – Shin-Kiba segment (which uses the former Keiyō Freight line) is elevated.

Construction of the line started in 1992, with the eastern end of the line using the right-of-way of the Keiyō Freight Line (abandoned in 1983). The first portion of the line between Shin-Kiba and Tokyo Teleport opened for service on March 30, 1996, initially under the name Rinkai Fukutoshin Line (臨海副都心線, Rinkai-fukutoshin-sen^?). The name was officially changed to the Rinkai Line on September 1, 2000. The extension to Tennōzu Isle opened on March 31, 2001 and the final portion to Osaki on December 1, 2002.