Before the Eagles' first men's sellout, 4,552 fans at Alico Arena, Bernard Thompson added 13 points.
Spurred by a 23-2 run, Florida Gulf Coast (1-1) led 32-25 at halftime.
"It's kind of what we expected," Miami coach Jim Larranaga said. "We haven't been defending very well and a couple of guys on the team need to shoot the ball well for us to open things up inside."
Despite making just 1-of-11 3-pointers, Florida Gulf Coast won thanks to a 40-14 margin in points in the paint and 40-32 edge in rebounds. The Eagles had six dunks.
Larranaga, whose team lost to Division II St. Leo in an exhibition, said, not having guards Durand Scott and Garrius Adams hurts his team's quickness. While Adams is bothered by an injury, Scott must sit out one more game due to an NCAA suspension.
"It's not a wake-up call," Larranaga said. "It's more a deficiency. We're slow. We're not a quick team. We were expecting to be quicker. We thought our big guys, who are in better shape than last year, would be able to run the floor better. Right now, teams are outrunning us. They're light on their feet. We're heavy on our feet."
Florida Gulf Coast lost its opener at Virginia Commonwealth 80-57.
"We knew we had to go out and play hard," Brown said. "These guys are bigger and lot stronger. We beat them with heart."
Eagles coach Andy Enfield said his team's ability to get loose rebounds were key. "We were poor on our opener," he said. "We gave up 25 extra possessions (to VCU). Tonight, we reversed that."
Kenny Kadji added 13 points for Miami, which shot just 29.1 percent from the field (16 of 55).
Florida Gulf Coast, which is in just its second season of being NCAA eligible, lost by one point to Nebraska, Texas Christian and Southern Methodist last season before making a late run and reaching the Atlantic Sun Conference Tournament championship game.
Miami (1-1), led by Shane Larkin with 14 points, took a 15-5 lead but didn't make a field goal for an 8:44 stretch. Meanwhile, Florida Gulf Coast pounded the ball inside. A Chase Fieler dunk put the Eagles on top 18-16 and when Brett Comer made two free throws, Florida Gulf Coast led 28-17.
A Larkin 3-pointer tied the game at 39. However, the Eagles responded with a 10-3 run after a three-point play by McKnight. The Hurricanes couldn't recover.