"We have a set of standards that we expect people in our program to adhere to," head coach Shaka Smart said in a news release. "Tevin has failed to reach them."
Mack, a 6-foot-7 small forward, is the team's leading scorer at 14.8 points per game. He scored 27 points in a win over Oklahoma State earlier this month.
This is the second suspension for Mack this season. He missed an exhibition game and the season opener for a violation of team rules.
Texas has lost four of its past five games, including a three-point home loss to TCU on Wednesday. The Longhorns are 7-9 overall and 1-3 in the Big 12. Their next three games are against No. 10 West Virginia, No. 1 Baylor and No. 2 Kansas.