Kamara's neat finish 10 minutes from the end capped a much-improved second-half performance from the Dons after Andy Monkhouse's early goal had looked set to hand Mick Harford's hard-working side their first win in eight league games.
Danny Wilson made one change to the team that that lost 2-1 at Hartlepool last Saturday with Kamara coming into the midfield for Stephen Quinn, who returned to Sheffield United after the end of his one-month loan spell.
Rotherham had the better of the early exchanges but it was the Dons who came closest to breaking the deadlock in the eighth minute when Leon Crooks' pull back fell just behind Clive Platt five yards out.
The Millers' first chance was gifted to David Worrell three minutes later after Pablo Mills' poor defensive header dropped kindly for him on the edge of the box but the full-back's strike was deflected wide.
But the visitors' dominance was rewarded in the 24th minute when Monkhouse put Rotherham ahead.
The Dons' defence allowed Shaun Barker's long throw to bounce all the way through to the back post where Monkhouse turned it in unmarked from close range.
Milton Keynes fought back and Izale McLeod missed a good chance to put them back on terms when he skewed wide under pressure from just four yards, before the striker had a strong penalty appeal turned down when he appeared to be brought down by Barker as he raced clear in the 38th minute.
Kamara dragged another good chance well wide for the hosts just before the break after goalkeeper Gary Montgomery failed to deal with Dean Lewington's cross.
The Dons came out fired up for the second half and McLeod twice went close in the opening two minutes of the re-start.
First he forced Montgomery into an excellent fingertip save after spinning on the edge of the box and firing low and then the 21-year-old raced on to Matt Baker's long kick before blasting over the bar.
Montgomery had to be alert again to block Kamara's fierce drive after the Millers were caught napping by substitute Gary Smith's quick free-kick, before Paul Hurst cleared Mills' goalbound header off the line from Nicky Rizzo's corner in the 65th minute.
Kamara smashed another good chance just over the angle from 10 yards, before McLeod raced on to Lewington's through ball in the 77th minute but wastefully put his effort wide of the post when one-on-one with Montgomery.
But the Dons were not to be denied and three minutes later Kamara equalised with a neat first-time toe poke from 12 yards after latching on to McLeod's pass.