Despite trailing early, Chesterfield looked to find a response when both Jimmy Ryan and Eoin Doyle went close to finding an equaliser.
On the stroke of half time, their title hopes were nearly extinguished completely when Ryan Cresswell's close-range effort went agonisingly wide.
However, within six minutes of the restart Chesterfield were level thanks to a Sam Hird header after Jay O'Shea's pinpoint cross.
On 55 minutes, the Spireites completed the turnaround when a Gary Roberts strike from the edge of the box found the top corner of the Fleetwood net, to the relief and delight of the home crowd.
In the end, the Spireites held on to their lead and with it, claimed the title.