Substitute Tcham N'Toya-Zoa scored with his first touch as in form Chesterfield made it 3 wins on the trot.
A dire game finally sprang into life 8 minutes after the break when N'Toya scored just seconds after replacing Caleb Folan.
The congulese striker powered a header passed Mark Goodlad from Alex Bailey's corner for his 4th goal of the season.
And Vale's night went from bad to worse 4 minutes later when they were reduced to 10 men.
Defender Dean Smith was sent off for a professional foul after he brought down N'Toya as the front man went clean through on goal following a fine solo run.
Earlier valiant's striker Billy Painter almost broke the deadlock when he forced a fine stop out of Cal Muggleton with a powerful half volley from 20 yards.
But Painter's effort in the 46th minute was the first time either goalkeeper had been forced into action after an abissmal first half.
Martin Foyle's men tried hard following N'Toya's strike but the home side held on to claim a deserved win and maintain their 100% home record.
Afterwards a disappointed Foyle said "The first half was ok but the second half turned out to be a bit of a nightmare.
Our passing was poor and we had no one that could run at people.
We came here to try to tighten up our away record.
But we conceded a poor goal. Their big lad (Folan) came off, and the small lad (N'Toya) scored from a header." Foyle also criticised the sending off Smith in the 57th minute. He said "he should never have gone, there was another defender 3 yards behind him. It was a booking but never a sending off. I have tried to appeal a few things this season but the FA turned a blind eye.
Overall the whole team performance was poor."