The 27-year-old Samoa international joined Sale in January 2015 and has gone on to score six tries in 24 games.
Sharks director of rugby Steve Diamond said: "TJ has been a revelation since he joined us.
"His performances for Sharks were monitored by other clubs but he wanted to stay with us and help us achieve our goals of becoming one of the leading teams in the Premiership."
Flanker TJ Ioane has signed a new three-year deal with Sale Sharks.