Aaron Anderson tacked on 16 points and Josh Schuler and Alonzo Traylor had 11 apiece for second-seed North Dakota (16-15), which moves on to the semifinals against a team to be determined based on the seeds of the advancing teams.
Mikh McKinney netted 24 points for seventh-seed Sacramento State (14-16). Dylan Garrity contributed 18 points and Cody Demps finished with 15.
The Hornets led 42-39 at halftime after shooting 55.6 percent from the floor, including a perfect 4-of-4 mark from 3-point range, in the first half. North Dakota stayed close, sinking 48.4 percent.
The tables turned in the second half, with North Dakota heating up to 56 percent and Sacramento State cooling to 37 percent shooting. Anderson hit a layup with 3:15 to play that pushed North Dakota ahead 73-72. North Dakota then went 7-of-8 at the free-throw line down the stretch to hold on.
North Dakota had a 38-28 scoring edge in the paint.