Jennings redeemed himself after missing a 3-pointer at the regulation buzzer that would've won it, helping keep the Bucks very faint playoff hopes alive and snapping Philadelphia's three-game winning streak.
Milwaukee is 3½ games behind Indiana for eighth place in the Eastern Conference with six games left.
The Sixers hoped to start building some momentum after clinching their spot in the playoffs Friday, but took an early double-digit lead and then came out flat in the second half despite 20 points and 12 rebounds from Elton Brand.
Milwaukee had lost three of four and trailed by 12 in the first half, but Keyon Dooling and Salmons hit consecutive 3s and Salmons followed a few minutes later with a jumper that made it 76-69 midway through the fourth.
Philadelphia answered, and Brand's 11-footer off an assist from Jrue Holiday tied it at 79 with 1:42 to play. Holiday threw the ball away in the final seconds, giving Milwaukee a final chance, but Jennings' 3-pointer bounced harmlessly off the front rim to send the game to overtime.
From there, Jennings took over.
He hit a 3, made a layup and an awkward 10-foot floater with 26 seconds left to give Milwaukee an 89-85 lead. The Sixers never got a chance to tie from there as Jennings hit two free throws to end it.
After a 3-13 start, Philadelphia completed the first part of its turnaround season by reaching the playoffs in its victory over New Jersey on Friday night.
Sixers coach Doug Collins said he had no plans to rest anyone leading into the playoffs with just one more road game and four at home to end the season with his team seemingly locked into sixth place.
Philadelphia will start the postseason on the road, likely against either Boston or Miami. But this performance was a question mark for a team that said it didn't want to let up the rest of the regular season.
NOTES: Milwaukee's season-long injury woes continued. F Carlos Delfino (upper right ribcage), F Ersan Ilyasova (concussion) and F Jon Brockman (left shoulder) were all out. The Bucks have missed a combined 266 games due to injuries, illness or suspension. ... Philadelphia has had 40 total games missed due to injury, illness or suspension. ... Sixers G Lou Williams strained his right hamstring in the third quarter and did not return.