Hamilton led from start to finish in France and also claimed the fastest lap, with teammate Valtteri Bottas finishing second, Eurosport reported.
Bottas has won the two races in 2019 which Hamilton hasn't added to his collection. Ferrari's Charles Leclerc was third.
There was little to worry about for the Mercedes duo for the first half of the race, with only a mild complaint from Hamilton over his seat.
Max Verstappen, starting in third, dropped down to fifth as the in-form Sebastian Vettel moved up into second, with Leclerc in fourth after he pitted ahead of his team-mate. Verstappen repeatedly complained that his engine was failing to offer him enough to challenge.
Ferrari were able to move Vettel onto a one-stop strategy as teams began to favor a harder compound to see out the race, with the French heatwave giving all teams a job in managing the graining on their tire – and Verstappen was able to reclaim fourth. Leclerc ultimately moved back up into third.
Hamilton pulled away from even Bottas as he extended his lead to 12 seconds by lap 31, with the pair swapping fastest laps and a bonus point for much of the race. With four-fifths of the race run, Hamilton complained that his own tires were blistered, forcing him to take care to bring his car home – a consistent theme of the campaign so far.
The win moves Hamilton further ahead of Bottas at the top, but Vettel – fifth – will regard this as another missed opportunity this season. He had the pace, but was fighting against his poor qualification from the start.