Les Bleus were favourites going into the final but Croatia didn't make it easy for Didier Deschamps' men.
The World Cup final debutants will point to some controversial VAR decisions as damaging their bid for glory after a pulsating clash in Moscow.
The victory at the Luzhniki Stadium gives France their second world title - 20 years after they first won the award under Deschamps' captaincy on home soil in 1998.
Kylian Mbappe wasn't even born when France won that tournament, but he was on the scoresheet this evening, netting the fourth goal as Les Blues edged toward glory.
Paul Pogba and Antoine Griezmann also found the net, with an own-goal from Mario Mandzukic opening the scoring for the eventual winners.
Ivan Perisic cancelled out that opener with a stunning strike but Croatia couldn't match France's potency in front of goal.
Mandzukic made up for his own-goal by scoring Croatia's second after a huge blunder from Hugo Lloris gifted him the ball.
But there wasn't to be a dream comeback for the Balkans side, leading to wild celebrations on the pitch in Russia and back home in Paris and across the whole of France.
There was joy too for England striker Harry Kane, who was confirmed as the Golden Boot winner at full-time.
His six goals proved to be enough, with Mbappe and Griezmann both needing hat-tricks in the final to catch him.
France led 2-1 at half-time after Mandzukic's own goal and Griezmann's controversial VAR penalty, with Perisic briefly bringing Croatia level.
Quickfire strikes by Pogba and Mbappe midway through the second half put France on course for the title but then Mandzukic was gifted a goal by French keeper Lloris to set up a nervous last 20 minutes.
France, however, withstood a spirited Croatia assault to lift the trophy for the second time and ensure there was no repeat of two years ago when they were beaten in the European Championship final by Portugal in Paris.
The victory means that Deschamps, captain of the 1998 side, becomes the third man to win the World Cup as player and coach after Brazil's Mario Zagallo and Germany's Franz Beckenbauer.
It was the highest-scoring final since England beat West Germany 4-2 after extra-time in 1966 and the highest in normal time since Brazil beat Sweden 5-2 60 years ago.
The landmarks came thick and fast in the first half too.
Croatia had started full of energy but fell behind when Mandzukic, who scored the extra-time winner against England in the semi-final, became the first man to score an own goal in a World Cup final when a Griezmann free kick skidded in off his head in the 18th minute. It was the 12th own goal of the tournament.
That meant it was the fourth successive knockout game that Croatia had conceded first but Perisic, who got the equaliser against England, was on hand again to level the scores 10 minutes later, smashing in a low shot after Sime Vrsaljko had headed Luka Modric's free kick across the box.
But it was then Perisic's turn go from hero to zero when he flapped an arm at a corner and, after a VAR review, Argentine referee Nestor Pitana awarded the 28th penalty of the tournament, another record, which Griezmann stroked home in the 38th minute for his fourth goal of Russia 2018.
That made it the highest-scoring first half since 1974, when West Germany led the Netherlands 2-1 - also the final score then.
It was harsh on Croatia, who had made most of the running, and they were on top again after the break, continually winning their one-on-one duels in the air and in every tackle and forging forward in the French box with plenty of variety.
But France's defence, so impressive all tournament, held and they went 3-1 up on the hour as Mbappe and Griezmann combined to set up Pogba on the edge of the box. His right-footed shot was blocked but he coolly curved the rebound in with his left.
After three successive extra-time knockout games the chances of another Croatian comeback seemed slight but they looked dead and buried six minutes later. Lucas Hernandez tore down the left to set up Mbappe who drilled a low shot beyond keeper Danijel Subasic for the 19-year-old's fourth goal of the tournament.
An awful blunder by Lloris revived Croatia, as the French keeper tried to dribble around Mandzukic only for the striker to tap the ball straight into an unguarded net.
Croatia, beaten by the French in the semi-finals in their first World Cup appearance in 1998, continued to press but their energy was sapped and France safely held out for the victory.
