Zlatan Ibrahimovic led the way for Laurent Blanc's side, scoring twice in the first half to send PSG well on their way to victory, with Sebastien Squillaci's 20th-minute red card providing an early boost for the defending champions.
Edinson Cavani, a second-half substitute, followed suit, scoring two of his own in the final 10 minutes to wrap up an easy win and claim the league cup.
PSG are still active in the Ligue 1 title race, Coupe de France and UEFA Champions League, and Matuidi has urged his team-mates not to get carried away with Saturday's success, as the France ace eyes a treble - or better.
"That [winning on Saturday] was the goal. Now all is well for us," he told France 2.
"We played to win; it was a very good game. We had control and opportunities.
"This is the first title, now we will go for the second and why not the third?
"It was important to win for confidence - we are very happy.
"We will celebrate in the locker room and then quickly get to rest, because we have a big game next against Barcelona. We must quickly re-focus."
PSG host Barcelona in the first leg of their UEFA Champions League quarter-final on Wednesday.
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