Matty Kosylo marked his return from suspension with the goal that put Halifax ahead, but Denton cancelled it with a trademark header shortly afterwards.
Town could have snatched it in added time, but Kyle Wootton headed against the bar.
Halifax produced a gutsy performance with plenty of attacking intent in what was, at times, an absorbing encounter that ebbed and flowed in-front of more than 2,000, and BT Sport, at The Shay.
Jordan Preston, Matty Brown and Ryan Sellers all missed the game, presumably through injury, although Matty Kosylo did return after his three-game suspension.
The Shaymen started with a 3-4-1-2 system, with Niall Maher, Nathan Clarke and Joe Skarz in defence, Jacob Hanson and Kosylo on the flanks and Dayle Southwell tucked in-behind Kyle Wootton and Jonathan Edwards up top.
It was an attacking line-up, with Josh Staunton screening in-front of the back-four, and keeping a very close eye on the returning Denton.
Will Evans had a goal-bound shot blocked inside the area within the first minute, after Denton had won his first header within the first 10 seconds.
But that proved a false dawn for The Spireites, who were largely second best in the first-half, with Town looking the likelier to score.
Three crosses from the right in quick succession highlighted where The Shaymen were getting most joy, and where Chesterfield were getting caught out, with Hanson repeatedly bursting down the flank unopposed.
From his cross, the ball was headed over at the far post only yards from goal, while another of his crosses was scrambled away after being fired through the box.
Between those, James Berrett had regained possession and played in Southwell down the right, but he couldn’t find Edwards or Wootton at the far post waiting to convert the chance.
Skarz then fired a driven shot just wide of the post after a corner was cleared to him 30 yards out.
It wasn’t all Town; Denton headed one of Sam Muggleton’s extraordinarily long-throws onto the top of the bar, while debutant Alex Kiwomya should have done better than directing Lee Shaw’s cross well wide from the middle of the box.
Most of the football was fairly route-one, but there was generally more finesse to Town’s play than Chesterfield’s, with the fleet-footed Hanson and Edwards in particular a real threat, while Southwell saw the ball in some dangerous pockets of space in-front of the Chesterfield defence.
Halifax possessed more pace than the visitors, and used it to good effect at times, but again just needed a goal to show for having been in the ascendancy.
Denton had been handled effectively; Chesterfield boss Martin Allen felt he was handled too roughly by Town at times, although the home supporters argued it was the other way round.
Curtis Weston had a golden opportunity a few minutes after the interval when substitute Zavon Hines picked him out at the far post, but he could only put the ball wide from three yards.
Both teams seemed to get to grips with each other more in the second-half though, with Town less effective going forward, as passes went astray or runs were caught offside.
But the commitment and effort, through headers away or throwing bodes in-front of shots, was there.
And it was rewarded when Wootton’s Denton-esque flick-on from Sam Johnson’s long ball directed the ball perfectly into Kosylo’s path, who then rounded Callum Burton and stroked the ball home.
Kosylo was on target the last time the BT Sport cameras were here just over a year ago, and kept his cool to make sure he was again.
But the lead lasted only 10 minutes as substitute Jerome Binnom-Williams’ cross was headed back across goal and in by Denton.
Who’d have thought a former Town striker would score against his old club, eh?
At the next break in play, a streaker charged the full length of The Shay pitch to grab his moment in-front of the cameras.
When play resumed, the momentum appeared to be with Chesterfield as Hines’ low shot was saved by Johnson, before Denton headed wide from a free-kick.
Substitute Michael Duckworth’s tenacity sparked a rapid counter-attack which saw Kosylo play in Edwards, but Burton kept out his low drive from an angle.
Wootton then came within inches of netting the winner when his header from a corner crashed off the bar and bounced down right on the line.
Halifax: Johnson, Hanson, Clarke, Maher (Lenighan 44), Skarz, Staunton, Berrett (King 61), Edwards, Southwell (Duckworth 78), Kosylo, Wootton. Subs not used: Rowley, Odelusi.
Scorer: Kosylo (69)
Shots on target: 2
Shots off target: 5
Chesterfield: Burton, Muggleton, Maguire, Evans, Smith, Rowley, Weston, Reid (Binnom-Williams 67), Kiwomya (Hines 46), Shaw (Fortune 90), Denton. Subs not used: Hollis, Kayode.
Scorer: Denton (79)
Shots on target: 2
Shots off target: 9
Referee: Marc Edwards
Town man of the match: Jacob Hanson