Having suffered a mini-blip prior to Saturday's Coupe de la Ligue triumph, which had seen them bow out of the UEFA Champions League before losing to Lyon in Ligue 1, PSG were far from their best at the Parc des Princes on Wednesday.
Evian had knocked PSG out of the Coupe de France last year before beating them this season in the reverse league fixture.
However, there was no such slip-up for Laurent Blanc's men this time out as they moved 10 points clear of second-place Monaco thanks to Matuidi's cool finish.
The winner came with a minute left via a Lucas Moura throughball, after the visitors had seen Kassim Abdallah sent off for a second bookable offence.
Victory means that PSG will clinch the title with three points at Sochaux on Sunday, although if Monaco lose against already-relegated Ajaccio a day earlier then Blanc's men will be confirmed as champions without even taking to the field.
Elsewhere on Wednesday, Toulouse and Lyon played out a goalless draw at the Stadium Municipal, with the visitors unable to pile the pressure on Saint-Etienne in the battle for fourth place.
With those around them having drawn at the weekend, victory would have put Lyon behind Saint-Etienne only on goal difference.
However, going into the final four games of the season, Remi Garde's side sit are now two points off a UEFA Europa League spot, while Toulouse remain on course for a top-half finish.