Grimsby came from behind to secure victory at Dartford and book themselves a place in the Blue Square Bet Premier play-offs.
The Darts broke the deadlock through Jack Evans after he prodded the ball home from close range.
Andy Cook levelled the game with a spectacular 30-yard effort in the 79th minute and this spurred his side on.
Aswad Thomas converted a corner from close range, but Grimsby also had Joe Colbeck sent off for violent conduct.
VIEW FROM THE DRESSING ROOM
Dartford manager Tony Burman told BBC Radio Kent:
"It's the experience of a full-time side. They see games out, they keep plodding away and we had the opportunities to go 2-0 and where we didn't take them, we paid the price.
"Their keeper has had some great games against us. He pulled off a fantastic save in the first half and an equally fantastic save from Danny Harris at 1-1.
"It's disappointing to have a 1-0 lead and lose 2-1, but you've got to play for 90 minutes and whatever happens you must believe you can win.
"You've got to be intelligent enough to keep the ball and know you can't give away silly free kicks."
Grimsby Town joint-manager Rob Scott told BBC Radio Humberside:
"Delighted to have reached the play-offs but more delighted with the attitude that they showed second-half to get the win. When it went to 1-1 many a team would have settled for that, but not this group.
"The lads are struggling at times. We're not going to come out and say exactly what is this, that and the other - we're certainly going to look after the players because we see them day in and day out and we know where they are fitness wise.
"I've been pleased with everybody tonight."