The Spireites secured promotion to Sky Bet League 1 with a 2-0 victory at Burton Albion following two second-half goals from Jay O'Shea.
O'Shea struck soon after the re-start and sealed the win with a second goal in the 79th minute.
The win took Chesterfield back to the top of the table, meaning that victory at home to Fleetwood Town next weekend would secure the title.
Chesterfield had the first chance of the match when Gary Roberts' free-kick was met by Liam Cooper, whose header was deflected over.
Burton's Billy Kee tried an ambitious overhead kick which saw the ball sail over the bar.
Matty Palmer then threatened inside the area before Cooper made an important interception and cleared the ball.
O'Shea's incisive through ball picked out Eoin Doyle inside the area, but as the striker shaped up to shoot, Callum McFadzean made a vital block.
Paul Cook was forced to make a change in the 20th minute when Daniel Kearns went off after picking up a knock. He was replaced by Dan Gardner.
Cooper had featured at either end early on and he made another vital clearance as Kee waited to pounce inside the area.
Another enforced change was made in the 29th minute when Cooper was helped from the pitch after landing awkwardly and picking up an injury. Ritchie Humphreys joined the action, taking up a central midfield role with Sam Hird dropping back to partner Ian Evatt in Cooper's place.
Burton keeper Dean Lyness was called into action for the first time, palming away Doyle's cross-cum-shot and then O'Shea had an angled shot deflected wide.
The home side then had their first effort on goal, a tame header from Kee which was easily dealt with by Tommy Lee.
Hird went close to scoring in the 40th minute when he directed a firm header on target from Gardner's corner but Lyness came to Burton's rescue, tipping the ball onto the bar.
The breakthrough came in the 52nd minute when Humphreys slipped the ball through to O'Shea who slotted past Lyness to the delight of the Chesterfield fans behind the goal.
There was a worrying moment at the other end when Kee found himself in space inside the area, forcing Lee to make a near post save.
Lee was also called into action to save a header from Marcus Holness.
As the Spireites went in search of a second goal, Roberts put a free-kick just off-target.
Burton skipper Lee Bell then fired in a volley that was thankfully straight at Lee.
Doyle threatened to find a way through inside the area before Holness nipped in to clear for a corner.
Ashley Hemmings and Zeli Ismail both put free-kicks over before O'Shea put the Spireites further ahead. The goal came when Doyle's low driven cross was pushed away by Lyness and O'Shea headed home the rebound.
O’Shea had a couple of opportunities to seal his hat-trick but Lyness was equal to the efforts.
With time ticking, Chesterfield maintained possession and saw out the game comfortably to the delight of the travelling supporters.