The 6-footer led the Lady Vols with 14.9 points and 5.3 assists a game last season while shooting 42%. Westbrook started all 64 games she played at Tennessee.
The sophomore was a Southeastern Conference all-freshman pick in 2017-18.
Westbrook won a gold medal with the U.S. national team at the 2016 FIBA Americas U18 Championship, where she was a teammate of current UConn player Megan Walker.
Westbrook is among four UConn newcomers, joining freshmen Aubrey Griffin and Ania Makurat and graduate transfer Evelyn Adebayo.