The Spireites will face Notts County in the National League Promotion Final after beating Bromley 3-2 in extra-time.
An own goal from Ayodeji Elerewe, a Darren Oldaker free kick and a fine finish from Liam Mandeville gave Chesterfield victory.
Paul Cook named an unchanged side from the 4-0 win over Maidstone United on the final day.
The first chance of the game fell to Chesterfield. Bailey Clements played the ball forward to Armando Dobra, who saw his shot blocked.
Chesterfield came forward again soon after. Jeff King slid through Mandeville, who forced a good save from Reece Charles-Cook.
After a stoppage in play for a medical emergency, Bromley’s Michael Cheek was booked for a foul on Dobra.
The Ravens almost found themselves in front against the run of play. Jude Arthur’s free kick found Cheek, who headed just wide.
Nine minutes into a lengthy 11 of injury time, Bromley struck first. Adam Marriot turned the ball in on the line despite a good save before from Ross Fitzsimons.
The first half came to an end, with Chesterfield the better side but trailing.
Under a minute into a second half, the Spireites were denied an equaliser. The ball fell to Mandeville in the box, who saw his shot brilliantly blocked by Ryan Stirk to keep the visitors ahead.
Bromley almost doubled their advantage two minutes later. Stirk’s corner was headed just over by Cheek.
Ash Palmer received Chesterfield’s first booking of the match. Marriot was pulled down on the counter, with the referee cautioning Palmer.
Chesterfield levelled the game after 58 minutes when a Ryan Colclough cross caused Elerewe to turn the ball into his own net.
The visitors almost restored their lead soon after. Kellen Fisher struck a fierce shot at Fitzsimons who palmed the ball away.
Bromley were reduced to ten men with 15 minutes to go. Elerewe was sent off for a high and late challenge on Mandeville.
After 80 minutes, Chesterfield took the lead. A free kick on the edge of the box was fired home by Oldaker to delight the home crowd.
Cook looked to the bench to close out the game. Ollie Banks and Paul McCallum were introduced for Dobra and Dallas.
Following this, Joe Quigley replaced Mike Jones as the game entered a lengthy ten minutes of injury time.
Nine minutes into injury time, Chesterfield hearts were broken by an equaliser. Cheek was the first to the ball, following a headed Omar Sowunmi cross, and poked home for Bromley.
The referee’s whistle ended the 90 minutes and confirmed extra time.
The Spireites had the first chance of the additional period. Good feet from King allowed him to get a shot away but it was blocked well.
Laurence Maguire became Chesterfield’s final change when he replaced Clements.
It was delight again for Chesterfield when they regained the lead on the 102-minute mark. Mandeville ran through and smashed the ball home after Bromley failed to clear.
Quigley came close to securing victory with ten minutes to play. King found the substitute in the box, who saw his shot held by Charles-Cook.
The referee’s whistle finally confirmed Chesterfield’s place in the final against Notts County next Saturday.
Spireites: Fitzsimons, King, Palmer, Grimes ©, Clements (Maguire 96), Jones (Quigley 90), Oldaker, Mandeville, Dobra (Banks 85), Colclough, Dallas (McCallum 85).
Unused substitutes: Covolan.
Attendance: 9,657 (707 away).
