Ridley, who was averaging a double-double (12.7 points per game, 10.0 rebounds per game as well as 3.4 blocks per game) for the 8-3 Longhorns', suffered a fractured left foot in practice on Sunday and will have surgery Tuesday in Austin.
Ridley is out indefinitely and could miss the rest of the season.
The Longhorns, who have won six straight games, face UConn (8-3) at 8 pm CT Tuesday at the Erwin Center.
Ridley led the team in scoring four times this season, including three times in the six-game win streak and led UT in rebounds in all 11 games this season. Ridley posted a school-record 9 blocks in a win over Appalachian State on Dec. 15.