Drew Talbot tapped in just seconds into the second half before substitute Danny Whitaker's first touch doubled the lead and Tendayi Darikwa rounded off a second 45 to remember for the home fans.
Jay O'Shea had an early shot parried by Michael Ingham and the York keeper did even better on 20 minutes when he dived full length to his left to turn a glancing header from Chesterfield skipper Sam Hird round the post.
Chris Smith put a header wide from eight yards as the visitors threatened and Michael Potts had Chesterfield keeper Tommy Lee at full stretch to hold a low drive from 20 yards on the half hour.
The nearest either side came to a first-half goal came two minutes before the break when Louis Boa Morte shot narrowly over the bar after O'Shea set him up.
It took Chesterfield just 50 seconds of the second period to break the deadlock, Mark Randall's curling free kick evading the York defence to leave Talbot a tap-in from close range.
York were convinced they should have been awarded a spot-kick chance to level three minutes later when Jason Walker went down under a challenge from Liam Cooper, only for referee Chris Sarginson to deny their appeals.
Chesterfield substitute Whitaker added a second with his first touch of the ball, less than a minute after replacing Conor Townsend in the 74th minute. Boa Morte's free kick was blocked by Jamal Fyfield but Talbot picked up the loose ball and set up Whitaker to score.
In the 77th minute it was Whitaker who turned provider, beating keeper Michael Ingham to an underhit back pass to feed Boa Morte. He was crowded out but Darikwa was on hand to smash the ball home.