The Tommies (8-4 overall, 8-0 MIAC) has now won five games in a 10-day January stretch, four on the road. Coach Steve Fritz' team, which won at Robertson Center for the first time in five seasons, never trailed after taking a 9-0 lead.
The Toms own a 2.5-game lead over Gustavus (5-2) and a 3.5-game lead on Carleton, Bethel and Augsburg (all 4-3) near the midway point of the 20-game MIAC race.
UST had a 48-33 rebounding edge to offset 12 3-pointers made by Bethel.
For the Tommies, junior Joey Shimek added 16 points and six rebounds, junior Sean Sweeney had 14 points, five rebounds and four assists and senior Neal Anderson had 12 points. Soph Bryan Schnettler scored nine points off the bench, all in the first half.
Sweeney converted a three-point play to close the first half with a 42-35 lead, then sank a 3-pointer to open the second half.
Bethel pulled within 57-55 with 10:25 left but never got closer. UST used a 12-3 run to build a 69-58 cushion with 2:50 to go.
Tim Gilbert scored 22 points for the Royals.
UST plays Saturday at St. Mary's (3 p.m.) and hosts Concordia-Moorhead Monday (7:30 p.m.).