Bryce Dejean-Jones and Katin Reinhardt had 15 points each for the Runnin' Rebels (20-7, 7-5 Mountain West), and Marshall finished with 11.
Colton Iverson scored 16 points to lead Colorado State (21-5, 8-3), which outscored UNLV 19-8 over the first 6:45 of the second half to tie the score at 40-all.
The Rebels pulled ahead by seven on Savon Goodman's layup at the 9:08 mark, but the Rams charged back with a 13-4 run to take a 55-53 lead with 3:18 remaining.
After trading baskets several times, and with the score tied at 59, Marshall grabbed a defensive rebound after Dorian Green's 3-point attempt missed.
The Rebels, who came in after rallying for a 72-70 home win over San Diego State on Saturday, were paced by Dejean-Jones and Reinhardt in the first half as the two led a 3-point barrage that saw UNLV hit 6 of 14 from beyond the arc. Dejean-Jones was a perfect 3 for 3 while Reinhardt hit 2 of 5.
UNLV also did a good job of contesting most of Colorado State's shots in the first 20 minutes, while getting good help on the boards from everyone. A 10-2 spurt put the Rebels up 22-12 with 7:00 left in the first half.
Colorado State, which eked out an 89-86 win on Saturday at Air Force, snapped a six-game win streak. The Rams are now 5-5 in true road games this season, including 3-2 in conference play.
UNLV is now 15-1 on Tarkanian Court this season, which includes 13 straight wins. In addition, UNLV is 33-1 in its last 34 regular-season games at home, and has won each of its last 15 regular season home games against Mountain West opponents.
The teams split the season series, as Colorado State defeated UNLV 66-61 at home on Jan. 19. The Runnin' Rebels lead the all-time series 34-11 and have won 10 of the last 11 meetings at the Thomas & Mack Center.