The ruthless Spireites bagged four times in the second-half, including two brilliant finishes from Ollie Banks and Tom Naylor, before Grigg added another from close-range and then he grabbed a superb one of his own with a clever fourth from a tight angle.
The result extends Town’s unbeaten run to 11 in the league and 12 in all competitions. This was also their fourth straight clean sheet in all competitions.
Second-placed Barnet equalised in the 96th minute against Solihull Moors, which means Chesterfield have a two-point lead at the top, having played one match fewer.
Before kick-off there was a minute’s silence for England and Manchester United legend, Sir Bobby Charlton, who passed away on Saturday, aged 86.
Paul Cook made five changes from the win against Kettering Town in the FA Cup 10 days ago. The main headline from the team news was that Ryan Boot kept his place in goal, with Harry Tyrer apparently injured.
The visitors were missing their top scorer Dipo Akinyemi, who has eight goals this season, due to injury.
The Minstermen came into this clash fifth from bottom but they came out of the traps the quickest, winning a couple of early corners. Lenell John Lewis had an opening but his volley at the back post was blocked behind by Tyrone Williams.
After a slow start, Chesterfield started to get into their stride and their first chance came midway through the half. Banks chipped a clever ball over the top of the York defence and Grigg beat the offside trap. The striker controlled it and cut the ball back for Armando Dobra, whose sliding effort was saved by goalkeeper Rory Watson.
Banks was looking the more likely out of everyone to open up the away defence, playing some sublime passes, but chances were hard to come by. Mike Jones fired over from distance just after the half-hour-mark, which highlighted how tough they were finding it.
As half time approached, Liam Mandeville’s deep corner was only partially cleared and Michael Jacobs tested Watson from the edge of the box but the away stopper was equal to it.
York had been well-organised, with plenty of men behind the ball, and they would have been the happier of the two sides at the break, but not after the full-time whistle.
Chesterfield had started the first 45 slow but they did not make that mistake again and they took the lead on 49 minutes.
Moments after Grigg smacked a header against the crossbar from Banks’ cross, the midfielder arrowed a brilliant low shot across Watson and into the bottom corner.
Town were now on top and they pushed for a second, Watson saving Jacobs’ deflected shot, as the hosts started to dominate.
And just after the hour-mark, they did get a second, and what a goal it was. Naylor met the ball on the volley from about 25 yards and it found the bottom corner with pinpoint accuracy. That is his sixth of the season - a career best.
With 20 minutes to go, it was 3-0. Banks swivelled and got a shot off from the edge of the box, which was spilled by Watson, and Grigg finished from close-range.
And Grigg grabbed his second of the night and eighth of the season on 82 minutes, pouncing on a heavy touch from keeper Watson, before superbly squeezing the ball in from a very tight angle, which took everyone by surprise. ‘Your defence is terrified’ rang around the ground as the whole Kop bounced up and down.
After a slow start to this game, the Spireites had been ruthless in the second-half and put York to the sword. They really did put on a show.
Chesterfield XI: Boot; Mandeville, Williams, Grimes, Horton; Jones, Naylor; Jacobs (Berry, 76), Banks, Dobra (Colclough, 68); Grigg (Curtis, 83)
Unused subs: Freckleton, Sheckleford.