Two goals either side of the break gave the Shrimps the advantage they were looking for after the Stags had fought their way back into the game after going down to an early own goal.
Morecambe's opener came after just five minutes when a Garry Thompson cross was fumbled by Mansfield 's goalkeeper Jason White and the ball squirmed over the line.
Morecambe came close again when Michael Twiss skewed a shot wide before Mansfield produced some lively moments. Left winger Danny Sleath twice forced Joe Lewis into good stops and Michael Boulding shot well wide from 20 yards out.
But Boulding was soon to be rewarded for his persistence when he equalised on 39 minutes.
David Artell's back pass put his keeper Lewis under pressure and his clearance only managed to strike Boulding and rebound into the back of the net.
Four minutes later however the Shrimps were back on top when Craig Stanley's 20-yard drive beat White low to his right to give Morecambe the lead at the break.
They then extended their lead five minutes into the second half when Carl Baker scored his first goal for the Shrimps from the penalty spot after Thompson was hauled down by Gareth Jelleyman.
The Stags tried to claw their way back into the game with Boulding forcing Lewis into another neat save before the keeper produced the stop of the game to tip away Steven Dawson's late lob.
In the end it was the Shrimps who should have scored again when Wayne Curtis missed a glorious chance and Jon Newby flashed a shot across goal after some good work from new signing Damien Allen.
In the end the Shrimps were worthy winners on a historic day for the League Two new boys.