The hot-shooting Vikings improved to 20-0 on the season and 14-0 in Midwest Conference play. Lawrence, the nation's only unbeaten men's team, was 34 of 62 (54.8 percent) from the floor, including 10 of 20 on 3-pointers.
MacGillis led the way by hitting 8 of 10 shots from the floor, including 2 of 3 on 3-pointers. His 12 rebounds are a career high.
All-America forward Chris Braier added 14 points and nine rebounds. He also had a game-high seven assists. Keven Bradley chipped in with 13 points and Ben Rosenblatt had 12.
Beloit's All-America forward, Josh Hinz, scored 17 points and grabbed 11 rebounds. Hinz scored nine of his points in the final 10:42 when the game was basically decided.
Lawrence went on a 9-0 run midway through the first half to grab a 26-12 lead and led 36-23 at the break.
The Vikings, who ran their home-court winning streak to 17 games, pulled away early in the second half and never looked back. Lawrence opened the second half with a 20-4 run to take a 56-27 lead with 12:38 left in the contest.
MacGillis had seven points during that stretch, with Rosenblatt adding five and Braier four.
Beloit (10-10, 6-7 MWC) never got closer than 23 points the rest of the way.
Lawrence is back in action next Wednesday when it travels to Carroll for a 7:30 p.m. game against the second-place Pioneers.