The Mariners made the best of difficult conditions at Blundell Park and they took the lead through Lenell John-Lewis midway through the first half.
Town went on to have the better of things for the remainder of the opening period but their visitors struck back with Chris Stokes’ equaliser just after the hour.
From then, it was anyone’s game but Grimsby went back in front when Craig Disley’s deft volley made it 2-1.
And that was how it stayed, with the Town defence holding off a late Forest Green rally to seal a deserved win.
Town boss Paul Hurst made just one change to the side that beat Nuneaton in the FA Trophy on Saturday, with Toto Nsiala coming in for the injured Aswad Thomas.
That meant a reshuffle in defence, as Carl Magnay moved from right-back to the left of the back four, with Nsiala slotting into the centre alongside Shaun Pearson and Parslow moving to the right.
James McKeown was behind them in goal, while the midfield of Jack Mackreth, Disley, Scott Brown and Nathan Arnold was unchanged from the trip to the West Midlands.
John-Lewis and Jon-Paul Pittman also kept their places in attack, while the subs were Paul Bignot, Ross Hannah, Scott Neilson, Craig Clay and Hamish Watson.
Forest Green made the long journey north looking to continue a good record which had seen them lose just two out of their previous 17 games.
Manager Ady Pennock had the vast Football League experience of big striker Jon Parkin among his starting XI, with fellow forward Lee Hughes among those kept in reserve on the visitors’ bench.
Others to watch out for in the away ranks would include attacker James Norwood.
Early free kicks for both sides were comfortably cleared by the opposing defence, before John-Lewis was caught offside as Town looked to launch an attack down the right.
A foul by David Pipe on Magnay gave the Mariners another free kick just inside the Forest Green half but the ball from it was cleared by Parkin after Nsiala had headed it on.
A strong wind made for tricky conditions and the Mariners were looking to get around that in the early stages by keeping the ball on the floor and building up play patiently.
Marcus Kelly wasted the opportunity though, hitting the Grimsby wall with his 30-yard shot. But a good chance for the visitors came when Morwood was fouled by Nsiala in a central position.
Pearson had to get his head to a cross from Chris Stokes with striker Kurtis Guthrie lurking behind but the centre-back did well and Magnay was able to keep the ball in play near the corner flag.
Norwood went down under a challenge from Brown on 15 minutes and his low free kick from midway inside the Town half found its way through to Parkin but he fired over the bar from 12 yards.
A late challenge by Parslow on halfway three minutes later led to another away free kick but Town were eventually able to clear their lines.
Pittman got his head to the ball at the near post but it landed on the roof of the net. The Mariners were yet to trouble visiting keeper Sam Russell but that almost changed when Magnay crossed from the left on 20 minutes.
That seemed to spark the hosts into life, as Pittman was denied soon afterwards following an excellent run into the box, before John-Lewis saw a shot pushed away for the first corner of the game.
And on 23 minutes, Town took the lead when a ball into the box from Magnay saw Russell come off his line but he could not clear it as JOHN-LEWIS got there first to divert it into the net.
Grimsby were now the team on the up and Arnold found himself in space through the middle soon after the goal but he could only find Russell from 30 yards.
Town won a corner when Danny Coles headed the ball out of play on the home right but they were unable to make it count, as Guthrie headed clear.
The keeper was alert though, coming off his line to make a good block. McKeown was called into serious action for the first time on 31 minutes when Parkin got to the ball first and cleverly pulled it back for Norwood, who was in space on the edge of the Town box.
A strong challenge by defender Luke Oliver caught Pittman and left him needing treatment from physio Dave Moore, although the striker was passed fit to continue.
Coles was shown the first yellow card of the evening for pulling John-Lewis back just inside the Forest Green half.
The next chance went to the visitors and came about through clever play by Norwood to control a cross from Stokes and create the space for a shot, which he went on to prod wide.
One added minute was signalled at the end of the half as Town won a corner through John-Lewis, although the flag-kick was headed clear.
That proved to be the last opportunity of the half, meaning Grimsby retained their one-goal advantage at the interval.
The striker failed to control it properly though and it ran out for a goal kick. No changes were made before the restart and Forest Green looked to have created the first chance of the second half when the ball was played to Guthrie inside the Town box.
Grimsby’s first opening of the half came when Brown threaded a ball through for Pittman four minutes in but the forward’s low shot was well saved by Russell, who dived to his right to keep it out.
Kelly’s kick looked to have found its way through to Parkin but referee Darren England blew for an infringement in favour of the Mariners. Parslow had to concede a corner at the other end after a cross from Norwood on the right.
Kelly’s kick was met by Guthrie but his header was comfortable for McKeown. Parkin dragged a shot wide at the near post for Forest Green, before a foul by Magnay gave the away side a free kick on the right on 56 minutes.
Brown earned a booking for a foul two minutes later but they were unable to create anything from it as a shot from Parkin was blocked after Stokes had taken the kick.
Town then broke quickly and Brown ran through the middle before laying the ball off to Mackreth on his right, who was thwarted by keeper Russell.
The hosts had been the better side so far but they were pegged back when Forest Green equalised just after the hour.
Kelly’s chip into the penalty area was not fully dealt with by the Mariners defence and after the ball was worked back, it eventually fell for STOKES to smash a volley home from 12 yards. A foul by Magnay saw him shown a yellow card and gave the away side a free kick near the edge of the Town box.
Parslow had to sweep the ball away after a low cross from Norwood, before John-Lewis was caught offside as he chased a ball from Nsiala.
Norwood had a shot blocked and Nsiala had to head a cross away as the away side began to get on top of the game.
A free kick in a similar position to the one which led to the visitors’ goal came on 71 minutes but this time, Parkin shot from it and could only watch the ball miss the target.
Pipe hacked the ball away for a Town corner a minute later as the game moved from end to end but Arnold could not pick out a man in black and white from the flag.
Clay replaced Brown as the Mariners made the first substitution on 73 minutes.
And within seconds, the hosts were back in front when an intelligent dinked ball from John-Lewis was met by DISLEY, who cushioned a brilliant volley past Russell and into the far corner of the net.
Forest Green responded well to falling behind for a second time and they were almost level again when Guthrie’s shot was blocked before McKeown was equal to Norwood’s follow-up effort from the edge of the box.
Pittman was penalised for a foul on Pipe on the Rovers right but the resulting free kick was cleared by Disley.
Elliott Frear then wasted an opportunity after getting on the end of a good pass from Stokes, with the away side still pushing for a second equaliser as the game moved into its final 10 minutes.
Both sides made a change soon afterwards, with Hughes replacing Norwood for the visitors before Neilson was sent on in place of Pittman for Town.
Dale Bennett was then introduced for Forest Green on 83 minutes, with Pipe making way.
A shot from Hughes was comfortably caught by McKeown at one end, before a Town corner at the other was cleared.
The away side almost had their leveller with four minutes to go, when a free kick from Kelly on the right was flicked on by Oliver but nobody in the green and black shirts of the Gloucestershire side could touch it into the net at the far post.
Four added minutes were signalled by the fourth official and Magnay was forced off after taking a boot in the face, with Bignot replacing him.
Forest Green pushed forward in a bid to rescue a point but Town held firm to collect all three and ensure a great start to the busy festive schedule.
The Mariners are next in action when they travel to Macclesfield Town on Boxing Day.