Lewis Hamilton repeated his pole-to-flag triumph of 2018 with a flawless drive to his fourth win in succession.
It was the 86th pole of his career for Lewis Hamilton, who won last year's race from pole.
Lewis Hamilton clocked a best lap in one minute and 32.738 seconds to outpace the Finn by just 0.069 seconds on a hot day at the Le Castellet circuit.
Sebastian Vettel won the Canadian race 'on the road' but was relegated to second place behind Lewis Hamilton of Mercedes by a five seconds time penalty.
Sebastian Vettel was punished for making an unsafe re-entry into the action after 48 laps of Sunday's race after running off track and across a strip of grass.
After the Canadian GP, Sebastian Vettel launched a tirade against the race stewards, and moved a number two sign from his car to Lewis Hamilton's vehicle.
Lewis Hamilton resisted intense race-long pressure on Sunday to secure a narrow, dramatic and emotional victory for Mercedes at the Monaco Grand Prix.
Lewis Hamilton dedicated his 85th pole position to Niki Lauda on Saturday at the Monaco Grand Prix.
Lewis Hamilton clocked an unprecedented lap in 1min 10.166sec to end Valtteri Bottas' run of three successive poles.
Lewis Hamilton approaches Thursday's Monaco Grand Prix opening practice in sombre mood, barely 48 hours after the death of Niki Lauda.
On fire in a burning cockpit: Formula One legend Niki Lauda, who died at the age of 70, will forever be known for his 1976 accident. But even the horrific crash could not shake the 1975 world champion's icy determination.
Niki Lauda won the Formula One drivers' world championship three times, in 1975 and 1977 for Ferrari and in 1984 with McLaren.
A deal to stage the race at the historic seaside resort circuit near Amsterdam has been signed for at least three years.
Lewis Hamilton's Mercedes team arranged for one of their F1 cars to park at the home of Harry Shaw, a 5-year-old from Surrey, who is set to lose his battle against a rare bone disease.
It was Lewis Hamilton's third win this year, the 76th of his career and his fourth in Spain following victories in 2014, 2017 and 2018.
Valtteri Bottas clocked a stunning track record lap in 1 min 15.406 sec to finish six-tenths clear of Lewis Hamilton
Ferrari's Charles Leclerc and Sebastian Vettel were a second adrift in third and fourth ahead of Max Verstappen in his Red Bull.