Jannero Pargo scored 11 points, all in the fourth quarter. The Hawks, playing without leading scoring Joe Johnson, leaned on their reserves, including veterans Tracy McGrady and Jerry Stackhouse, in the final period.
The Bucks, led by Brandon Jennings' 34 points, were ahead by 15 in the third quarter. Atlanta pulled ahead with a 15-3 run to open the final period.
McGrady, Pargo and Radmanovic hit 3-pointers in the run that gave Atlanta its first lead since the second quarter.
Drew Gooden, who had 24 points and 10 rebounds, hit two free throws with 1:16 remaining for a 92-92 tie. Josh Smith answered with a jam before Ersan Ilyasova scored on a tip-in for a 94-94 tie. Radmanovic took a pass from McGrady and hit the go-ahead 3.
After Smith rejected a shot by Gooden, Stackhouse made two free throws to add to the lead.
Smith had 24 points and 19 rebounds.
The Bucks, led by Jennings, closed the first half with a 13-2 run to lead 51-39 at the break. Jennings started the run with back-to-back 3-pointers. After stealing a pass from Smith, Jennings then added a running layup to cap his personal 8-0 run.
The Hawks cut the lead to 69-65 late in the third period before Jennings took over again, sinking two 3-pointers while scoring seven straight points to push the lead to 76-65.
The Hawks were without Johnson and backup shooting guard Willie Green. Each will miss at least two games.
Kirk Hinrich made his second start, joining Jeff Teague in Atlanta's backcourt.
After missing two games and the All-Star game because of tendinitis in his left knee, Johnson returned to lead Atlanta with 18 points in Wednesday night's 85-82 loss to Golden State. Johnson's knee was stiff after playing more than 37 minutes.
Coach Larry Drew said he wants to make sure Johnson's knee is stronger before he returns.
Green left Wednesday night's game with lower back spasms.
The Hawks, already missing centers Al Horford (torn left pectoral muscle) and Jason Collins (sprained left elbow), struggled early in the game without Johnson. Hinrich had five of Atlanta's 17 first-half turnovers.
Radmanovic had three 3-pointers for all of his nine points in the final period. McGrady had nine points and 11 rebounds.
? NOTES: Bucks G-F Mike Dunleavy missed the game. He returned to Milwaukee to be with his wife, who gave birth to a boy. ... The Hawks are 10-0 when Smith scores 20 or more points. ... The Hawks' 17 turnovers in the first half were a season high. They had only six turnovers in the second half. ... Beno Udrih had 12 points for Milwaukee.