A Calum Dyson double and first-half goal from Chris Clements saw the home side ease to their first win in five League Two games.
The Mariners took the lead when a scramble in the penalty area resulted in Tom Bolarinwa's header being cleared off the line, but only to former Stag Clements who bundled the ball home.
Sam Jones had a great chance to double the advantage after the break when Mansfield goalkeeper Jake Kean missed Clements' long ball forward, but Rhys Bennett got back just in time to block the midfielder's shot.
But Grimsby got their second when Dyson took the ball out on the right before charging his way into the box and finishing superbly beyond Kean.
Things went from bad to worse for the visitors when Evans was sent to the stands where he clashed with Blundell Park security staff.
Hayden White then saw red after bringing Bolarinwa down in the box, with Dyson converting from the spot to secure the home side's victory.
Match report supplied by the Press Association
Match ends, Grimsby Town 3, Mansfield Town 0.
Second Half ends, Grimsby Town 3, Mansfield Town 0.
Attempt saved. Yoann Arquin (Mansfield Town) left footed shot from the centre of the box is saved in the centre of the goal.
Substitution, Grimsby Town. Adi Yussuf replaces Tom Bolarinwa.
Corner,  Mansfield Town. Conceded by Danny Collins.
Attempt blocked. Yoann Arquin (Mansfield Town) right footed shot from outside the box is blocked.
Foul by Malvind Benning (Mansfield Town).
Tom Bolarinwa (Grimsby Town) wins a free kick in the attacking half.
Krystian Pearce (Mansfield Town) wins a free kick in the attacking half.
Foul by Callum Dyson (Grimsby Town).
Substitution, Grimsby Town. Luke Maxwell replaces Gavin Gunning.
Substitution, Grimsby Town. Brandon Comley replaces Jamey Osborne.
Foul by Lee Collins (Mansfield Town).
Callum Dyson (Grimsby Town) wins a free kick in the defensive half.
Attempt missed. Tom Bolarinwa (Grimsby Town) right footed shot from the left side of the box is too high.
Foul by Rhys Bennett (Mansfield Town).
Sam Jones (Grimsby Town) wins a free kick in the defensive half.
Foul by Yoann Arquin (Mansfield Town).
Zak Mills (Grimsby Town) wins a free kick on the left wing.
Second yellow card to Hayden White (Mansfield Town).
Goal!  Grimsby Town 3, Mansfield Town 0. Callum Dyson (Grimsby Town) converts the penalty with a right footed shot to the bottom right corner.
Penalty Grimsby Town. Tom Bolarinwa draws a foul in the penalty area.
Penalty conceded by Malvind Benning (Mansfield Town) after a foul in the penalty area.
Corner,  Mansfield Town. Conceded by James McKeown.
Attempt saved. Rhys Bennett (Mansfield Town) right footed shot from the left side of the six yard box is saved in the bottom left corner.
Gavin Gunning (Grimsby Town) is shown the yellow card for a bad foul.
Shaquile Coulthirst (Mansfield Town) wins a free kick on the right wing.
Foul by Gavin Gunning (Grimsby Town).
Substitution, Mansfield Town. CJ Hamilton replaces Alexander MacDonald.
Corner,  Mansfield Town. Conceded by Danny Andrew.
Goal!  Grimsby Town 2, Mansfield Town 0. Callum Dyson (Grimsby Town) left footed shot from the centre of the box to the bottom left corner. Assisted by Tom Bolarinwa.
Substitution, Mansfield Town. Joel Byrom replaces Alfie Potter.
Substitution, Mansfield Town. Yoann Arquin replaces Matt Green.
Attempt saved. Benjamin Whiteman (Mansfield Town) right footed shot from outside the box is saved in the centre of the goal.
Attempt saved. Matt Green (Mansfield Town) header from the centre of the box is saved in the centre of the goal.
Shaun Pearson (Grimsby Town) is shown the yellow card for a bad foul.
Matt Green (Mansfield Town) wins a free kick in the defensive half.
Foul by Shaun Pearson (Grimsby Town).
Attempt saved. Matt Green (Mansfield Town) header from the centre of the box is saved in the centre of the goal.
Corner,  Grimsby Town. Conceded by Rhys Bennett.
Mansfield Town manager Steve Evans was sent off as his 10-man side were soundly beaten at Grimsby.