The reigning champions were held to a goalless draw by Lille last time out and struggled to find their stride again in Wednesday's clash at the Parc des Princes prior to a late flurry of goals.
Timothee Pembele's first strike for the club in his fifth appearance got PSG off the mark after 18 minutes, but it took until 11 minutes from time for Mbappe to add a second from a few yards out.
Substitutes Idrissa Gueye and Moise Kean then joined the scoring as Thomas Tuchel's men picked up a third league win in seven outings, although they end the year in third place a point behind Lyon and Lille, who both won elsewhere.