French champions Monaco, one-time winners of the competition, again came unstuck in the final against their Parisian opponents and were left ruing their luck after having a goal ruled out with one goal in it.
PSG added a second 21 minutes in through Di Maria, who slotted the ball past Danijel Subasic following a fine pass from star man Mbappe.
A couple of half-chances for Monaco came and went, the best of which saw Rony Lopes's chip shave the PSG post shortly before the interval.
After having a goal of his own ruled out for offside, Cavani was celebrating a second of the evening late on with a clinical close-range finish to earn his side more domestic silverware.
PARIS SAINT-GERMAIN (4-3-3): Trapp; Dani Alves, Thiago Silva, Kimpembe, Yuri Berchiche; Rabiot, Draxler (Diarra 81'), Verratti (Lo Celso 70'); Mbappe, Cavani, Di Maria (Pastore 52')
MONACO (4-4-2): Subasic; Raggi, Jemerson, Glik, Sidibe; Rony Lopes (Diakhaby 73'), Moutinho (Ghezzal 80'), Fabinho, Tielemans (Jovetic 46'); Lemar, Falcao