Four-time champion Hamilton, in a Mercedes, finished ahead of Max Verstappen in a Red Bull and Ferrari's Kimi Räikkonen after starting from pole.
"Leading the field is where I want to be, so it's great to be back on pole".
Sunday's race will be the first French Grand Prix since Magny-Cours in 2008 and the first held at the southern Le Castellet circuit since 1990. "It is such a handsome place", he added.
Hamilton s Mercedes team-mate Valtteri Bottas, who was second in opening practice, was hit by a water leak in the afternoon and wound up seventh after being prevented from completing the second session.
"I am happy with it but I am always trying for perfection", he said.
Hamilton, armed with a new Mercedes engine, posted a best lap of one minute and 32.539 seconds to finish clear of the rest. The track is growing on me as well; the more you drive it, the more you get to enjoy it.More news: Cardi B and Offset Were Secretly Married Last Year
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Behind the top three teams, Sainz took seventh for Renault, Leclerc did well to take eighth for Sauber, Magnussen's Haas starts in ninth and Grosjean get tenth after bending his vehicle.
The session was immediately red-flagged and Ericsson, 27, emerged unscathed from his charred Sauber.
As the F1 Grand Prix Circus returns to France for the first time in a decade, it's Lewis Hamilton on pole after qualifying, alongside team mate Bottas.
Fernando Alonso, victor of the 24 Hour Le Mans last week, failed to get out of the first qualifying section, which culls the slowest five drivers, along with McLaren partner Stoffel Vandoorne and both Williams cars.
"Our performance has usually been so-so on Saturdays, with our average position in qualifying so far this year being 13th", said Alonso.
Brendon Hartley will start behind them for Toro Rosso due to penalties arising from a breach of the engine regulations, with the New Zealander using his fourth of the season.