The Bucks used a 10-2 run to take a 16-point lead at halftime.
Carlos Delfino added 16 points and Hakim Warrick and Charlie Bell each had 12 in Milwaukee's third win in a row. Bell fired in three straight 3-pointers late in the third quarter to keep the Bucks comfortably ahead.
The Heat's Dwyane Wade scored 23 points, including 11 in the first 4 1/2 minutes of the game, and Michael Beasley had 16.
Miami has lost four of five.