The victory kept PSG eight points clear at the top.
They also registered their 50th goal of the league campaign from 20 matches.
Monaco came away from PSG with a point in a thrilling 3-3 draw in the capital last weekend but they posed no similar threat just three days later.
Mbappe was on target in the 24th and 90th minutes with Neymar tucking away a penalty in first-half stoppage time.
Pablo Sarabia added another in the 73rd minute, just seconds after coming on as a substitute.
Ibrahima Bakayoko grabbed a late consolation for Monaco, beating the impressive Kaylor Navas in goal.
PSG coach Thomas Tuchel fielded his 'Fab Four' attacking stars in Mbappe, Neymar, Mauro Icardi and Angel Di Maria.
It was a decision which paid dividends when Di Maria floated over a cross for Mbappe to score the opener.
Monaco goalkeeper Benjamin Lecomte denied Mbappe on two further occasions in the first half.
Neymar made it 2-0 from the penalty spot in injury-time after Kamil Glik had fouled Layvin Kurzawa.
Sarabia's goal was set-up by fellow substitute Marco Verratti before Mbappe completed the rout of the club he had joined in 2015.
Rennes are third in the table, five points behind Marseille and 13 off PSG after a 1-0 win over Nimes.
Adrien Hunou scored the winner in the 64th minute to ensure a sixth win in the last seven games.
Nimes are second bottom, three points behind Amiens who drew 1-1 at home to Reims.