France's Matuidi headed home a Zlatan Ibrahimovic cross following a quick counter-attack on the stroke of halftime to send PSG level with Lyon on 35 points but top on goal difference.
Lyon only threatened PSG when a Lisandro Lopez volley hit the post in the 27th minute and the big-spenders deserved their victory, proving much stronger than the visitors.
"Lisandro's chance could have changed the match but then we played at a very, very high level in the second half," PSG right back Christophe Jallet told French channel Canal+.
"You don't have to get overexcited when everything is fine nor be depressed when you have bad times. All the squad just enjoy being first."
Lyon's Michel Bastos confirmed PSG's superiority but said his side would not surrender in the title race.
"It's a long way to go in the league. We know who are the favourites are but we will try to fight until the end," the Brazilian winger said.
At Parc des Princes, Lyon had the early possession but the first attempt on target was for PSG's Javier Pastore, whose shoot from close range in the 12th minute was parried away by Remy Vercoutre.
Lisandro Lopez went closer to scoring when he struck the post, without knowing at the time it was to be his side's only clear-cut chance throughout.
The Swede, who has scored 17 and set up four of PSG's 33 league goals so far, could have doubled the lead a minute later but Vercoutre denied him.
The 32-year-old, who has been the first choice at Lyon this term for the first time since he joined them in 2002, saved Pastore's superb strike in the 65th minute.
At Saint-Etienne, Lorient extended their winning run to a fourth game thanks to Jeremie Aliadiere's seventh goal of the season in the 20th minute and a Alain Traore header 18 minutes later.
