Gareth McAuley's second half goal ensured Lincoln a place in the play-offs for a fourth consecutive season. The Imps only needed a draw to be sure of finishing in the top seven, and with Peterborough already losing at home McAuley's goal sparked off celebrations among the home fans.
But Dale fought hard and fully deserved their late leveller. With better finishing, they might even have won.
Lincoln created chances early on but struggled to get the ball as Rochdale stroked it around the park. Imps' striker Marvin Robinson headed over from six yards and then Francis Green saw a 23rd minute shot pushed out by Dale keeper Matthew Gilks.
Then Nat Brown blasted a long-range effort which struck Gareth Griffiths and flew inches over.
Griffiths again denied the hosts in the 41st minute when he blocked a shot from Jamie Forrester after the Lincoln man beat three defenders.
Lincoln should have hit the front a minute before the break when a defensive mix-up allowed Forrester to set up Green, but with only the keeper to beat he shot straight at Gilks.
Rochdale pushed forward early after the break with Ernie Cooksey twice going close and then Chris Dagnall shot over from the edge of the box.
Rickie Lambert then beat Paul Morgan inside the Lincoln area only for City keeper Alan Marriott to block his shot with his legs.
Lincoln introduced midfielder Lee Frecklington in the 70th minute, switching to a 4-3-3 system. The change worked as they took control immediately. Lee Beevers spotted Gilks off his line and almost beat the keeper from 40 yards.
Then Lincoln went in front when a corner from Scott Kerr was headed home at the far post by McAuley.
Brown went close again for Lincoln in the 81st minute, but his shot went inches wide.
Rochdale hit back and two minutes from time Rickie Lambert's free-kick finished up in the top corner with Marriott stranded.