Goals from Julian Draxler, Angel Di Maria and an Edinson Cavani brace led PSG to a record fourth successive Coupe de la Ligue and a convincing triumph over Leonardo Jardim's swashbuckling top-flight leaders.
Reigning champions PSG are three points behind Monaco with eight games of the Ligue 1 season remaining and Meunier feels a damaging night in Lyon for the leaders could play into the capital club's hands.
"I hope we have been able to give a small blow to the morale of Monaco with this victory," the Belgium international told reporters.
"They still have a lot of matches to play, in April especially with the Champions League. We must stay on the lookout. We have our destiny in our hands."
Monaco tackle Borussia Dortmund in a mouth-watering Champions League quarter-final, while PSG's interest in the competition was sensationally ended when they succumbed to Barcelona's historic comeback at Camp Nou last month.
Meunier feels claiming silverware at the expense of their title rivals proves the humiliation in Catalonia no longer lingers for Unai Emery's side.
"For the outside world, yes [we proved a point]," he said. "There are quite a few people who said that Paris Saint-Germain's season was over because of the defeat against Barca.
"We had already seen a reaction of pride for me in [the 2-1 victory over] Lorient, and now in Lyon.
"We have a group that said we had to start from scratch to make a difference."