Matt Gray’s charges ended a three-game losing streak thanks to Beautyman’s 87th-minute winner at Gander Green Lane.
Josh Coley put the hosts ahead in the fourth minute before Andy Cook ended a four-game goal drought.
The EFL’s bottom club got off to the perfect start as Coley ran on to Aidan O’Brien’s pin-perfect pass in the fourth minute.
Bradford dominated possession in the first half, but failed to trouble Dean Bouzanis in the hosts’ goal.
Sutton defender Omar Sowunmi was forced off early in the second half when he was concussed blocking Clarke Odour’s strike.
Joe Kizzi almost turned Ash Taylor’s throw into his own net.
But City equalised just before the hour when Cook headed home.
The Bantams striker almost turned the game on its head moments after when he rattled the bar before nodding over later in the contest.
After soaking up the pressure, Beautyman stole the spoils late on when he headed home Craig Clay’s cross.