A first half Mani Dieseruvwe strike saw the Spireites win 1-0 and record their third straight reserve victory at home to a depleted Grismby Town side.
After pressure but few chances, the Spireites struck first through Dieseruvwe as the front man controlled a cross and then volleyed home from eight yards with defenders not getting tight enough.
Grimsby's Harry Clifton received a straight red in the second period for a reckless challenge as the Spireites were unable to turn their superiority into further goals.
The hosts dominated the opening stages to the game and their first half-chance came through Michael Onovwigun in the 11th minute. He rose highest to meet a corner but he was unable to guide his header on target.
Just over ten minutes later, the Spireites deservedly took the lead. After some patient passing build-up play between the front men, the ball eventually found its way to Dieseruvwe who controlled well and fired into the back of the Grimsby net.
The visitors rarely threatened the Chesterfield backline while the hosts continued to dominate the game as well as possession but were unable to add to the score line before the half time whistle.
Half time substitute Alex Cairns was called into immediate action two minutes after coming on when Jack Mackreth fired towards goal but he was able to make a comfortable save at his near post.
Chesterfield had a glorious chance to double their lead in the 55th minute after Dion Donohue won the ball from a defender and fed Jake Beesley through on goal, but Andy Warrington in the Grimsby goal managed to get down well to thwart the young forward.
Grimsby had another chance to level the match just after the hour mark when Mackreath this time was a beneficiary of an error from trialist Liam Graham but he could only fire his volley over the bar.
Beesley again had a chance to double the Spireites lead when he met substitute Derek Daly’s cross but his header drifted just wide of the post.
The visitors’ chances of finding an equaliser took a huge blow in the 71st minute when they were reduced to ten men after Harry Clifton was shown a straight red card for a nasty challenge on Graham.
Chesterfield continued to dominate the game and control possession well with George Milner especially playing well and drawing frequent fouls out of the visitors’ defence.
The Spireites had another chance to seal victory with seven minutes to go when after patient build up play, Tom Marshall found Donohue with fired over from 20 yards out with the goalkeeper scrambling back.
Chesterfield saw the game out comfortably to continue their unbeaten run in the Final Third Development League.
Chesterfield: Chapman (gk) (Cairns 46') - Graham, Talbot, Onovwigun, Marshall, Maguire, Donohue, Beesley, Dieseruvwe (Daly 46'), Orrell, Milner
Subs not used: Holmes, Greaves, Keillor
Grimsby Town: Warrington (gk) - Sibbick, Hurst, Brown, Sunter, Doig, Venney, Clifton, Sawyer, Mackreth, Jennings
Subs not used: Heath-Drury, Hough, Wroot, Lawis, Crowther
Chesterfield: Dieseruvwe 24'