Both sides named unchanged starting elevens from their semi-finals successes over Belgium and England respectively, with Ivan Perisic shaking off a knock to feature for the Croats.
And it was Croatia who started the stronger, forcing France to defend deep inside their own half as Perisic and Ivan Strinic caused problems down the left flank.
Fifteen minutes in Perisic ran clear again, only to see his weak cross cleared by Samuel Umtiti as Mario Mandzukic waited to pounce.
However, it was Les Bleus who broke the deadlock with 18 minutes played after Antoine Griezmann won a free-kick 25 yards from goal.
He curled the set-piece in himself with his left foot and the unfortunate Mandzukic rose to flick a header beyond Danijel Subasic into the corner of the net for an own goal.
Croatia responded strongly and were level just before the half-hour mark as a free-kick into the area caused chaos, before the ball dropped to Perisic who took a touch and rifled home a left-footed shot from just inside the area.
France were handed a chance to go back in front seven minutes before half-time as a VAR decision saw Perisic adjudged to have handled in the area, with Griezmann calmly sending Subasic the wrong way from the resulting spot-kick.
Early in the second half France keeper Hugo Lloris made a fingertip save to deny Ante Rebic, as the forward ran on to an astute pass from Ivan Rakitic.
Les Bleus responded with Paul Pogba feeding Mbappe, who sprinted past his marker before seeing his shot blocked by Subasic at his near post.
Soon after that Didier Deschamps opted to make a substitution as N’Golo Kante made way for Steven Nzonzi.
And the change paid dividends just before the hour mark as Pogba saw his initial shot blocked, before he curled home a superb left-footed effort to leave Subasic stranded and give France a 3-1 lead.
The game was all but over as a contest 25 minutes from time as the ball fell to Mbappe 25 yards out and his right-foot shot skimmed into the corner of the net to give Les Bleus a three-goal cushion.
Four minutes later it was 4-2 as Lloris collected a backpass and tried to take the ball past the closing Mandzukic, who stuck out a foot to divert it into the unguarded net.
However, try as they might, Croatia could not find another goal to pile the pressure on France, who celebrated a second World Cup triumph as the final whistle of the 2018 World Cup sounded.