He scored directly from a corner kick to give his side some of the reward which they deserved after giving Grimbsy a hard match and robbing of them of the chance of moving to the top of League Two.
Lambert was the star of the first goal as well when he took a free-kick which deceived goalkeeper Steve Mildenhall after 51 minutes.
The goalkeeper could not hold Lambert's shot and the ball was bundled into the net by defender Simon Ramsden.
Twice Grimbsy went in front. Firstly it was a disputed penalty by Ciaran Toner after 24 minutes.
The penalty was awarded following a clash between Mark Jackson and Michael Reddy.
Rochdale hotly disputed the penalty decision and Jackson received a booking for his protests.
Then with time running out, Paul Bolland took advantage of some sloppy defending by Rochdale and should have sealed it with his 81st minute shot past goalkeeper Matthew Gilks who had left his line and was stranded.
It seemed all over until in the dying seconds Lambert got his equaliser.
Rochdale can blame themselves for not having collected all three points and their first home win since November last year.
They had plenty of chances with Iyseden Christie in particular missing a couple that he would surely have scored on another day.
And Lambert went close several times as did skipper Gary Jones and altogether Rochdale had enough chances to do more damage to Grimsby.