Two long-range efforts from Jamie Winter and a typically clinical finish from Jamie Ward settled a keenly contested first round clash in front of a 6,000 plus crowd at breezy Saltergate.
It was only Chesterfield's second victory in the competition in 16 ties and their first FA Cup win at home since 1997.
But it might have been a depressingly familiar tale if Mansfield had put away an early chance when on-loan Nottingham Forest striker Emile Sinclair somehow managed to turn Nathan Arnold's low cross wide of the back post from five yards out.
On such key moments matches turn and the Stags found themselves behind when goalkeeper Paddy Gamble allowed a 30-yard free kick from Winter to bounce off his hands and into the top left corner.
It was an embarrassing moment for the 20-year old in front of more than 1,600 visiting fans and he was beaten two more times early in the second half as Chesterfield made their superiority count.
Mansfield found themselves exposed on the break when Jack Lester put in Lloyd Kerry on the left and the midfielder set up Ward, who steered his 11th goal of the season past Gamble's despairing right hand.
Any chance of a comeback was snuffed out in the 57th minute when Winter again took aim and this time left Gamble helpless with a 25-yard right-foot shot from the left-hand edge of the area that went just inside the keeper's left-hand post.
There was little he could have done to save it and from then on it was a case of whether the visitors could salvage some local pride.
To their credit, the Blue Square Premier team kept plugging away and, after missing a couple of decent chances, they pulled a goal back when Arnold cut in from the left and unleashed a low 25-yard shot that went inside the right-hand post 12 minutes from the end.