Two goals from Edinson Cavani and an Angel Di Maria strike secured the win in a match in which VAR once again caused controversy.
Cavani scored twice in last season's 4-1 final win over the same opponents and he needed just eight minutes to break the deadlock, sweeping home from the penalty spot after Kamil Glik was eventually penalised for a trip on Kylian Mbappe following a lengthy VAR delay.
With the injured Neymar not involved, Mbappe looked eager to take up the mantle of PSG's creator-in-chief, and his run and superb pass saw Di Maria double the lead before the break.
Radamel Falcao saw a header disallowed for offside after another VAR referral and Rony Lopes clipped the woodwork in the second half, but Leonardo Jardim's side rarely looked like staging a comeback before Cavani netted a stylish third of the match with five minutes left, as Mbappe picked up his second assist.
PSG have now won the trophy eight times, with six triumphs coming since 2008, and have taken the first step towards yet another clean sweep of domestic silverware.
After a dazzling pre-match light show, it was Mbappe who shone brightest early on against his old club, and it was his driving run into the box that drew a foul from centre-back Glik.
Referee Clement Turpin awarded the penalty but then changed his mind, only to go back to his original decision after a delayed consultation with VAR. In the end, Cavani made no mistake from the spot.
13 - Edinson Cavani has become the Coupe de la Ligue’s 3rd best goal scorer (13 goals, alongside Lilian Compan). Matador. pic.twitter.com/IBrUSEnRN1— OptaJean (@OptaJean) March 31, 2018
PSG survived some Monaco pressure before making it 2-0 with a slick counter-attack. Mbappe raced into space and played a glorious cross-field pass into the path of Di Maria, whose shot went beneath Danijel Subasic far too easily.
It was a goal that compounded Monaco's poor start, something that was underlined further when Lopes sprung the offside trap only to chip his effort wide with the goal at his mercy.
Falcao then thought he had grabbed a lifeline eight minutes before the break, when he beat Kevin Trapp to the ball to head in Lopes' cross, but the goal was ruled out seemingly for offside after another VAR check, much to the striker's frustration.
That moment did at least inspire some life from Monaco, with Lopes clipping the crossbar with a dipping effort early in the second half, before Mbappe wasted two one-on-one chances to make it a three-goal lead for PSG.
Cavani had a second goal disallowed correctly for offside but he was not to be denied, the Uruguay star collecting Mbappe's pass and firing beyond Subasic into the bottom-left corner, as PSG won their fifth trophy under head coach Unai Emery in what could prove his last season at the club.