Hamilton edged Mercedes team-mate Valtteri Bottas to take top spot for the 75th time in his career, but cut a subdued figure, admitting he was slightly frustrated at missing time.
"It would have been nice if it had continued raining all day but unfortunately it dried up just in time for the session", added the 20-year-old, referring to the washed out earlier practice.
F1 is returning to France for the first time in a decade and the Paul Ricard track is hosting its first elite race since 1990.More news: Mavs swap picks with Hawks to get Luka Doncic
"This place is lovely, it's really stunning down here", Hamilton said of a circuit that last hosted a grand prix in 1990 and represents a new challenge for a man who has won everywhere else on the calendar.
Hamilton, who held off Red Bull's Max Verstappen throughout the race, profited thanks to a five-second penalty handed out to Vettel and Bottas that saw the pair relegated to the back of the grid at the start of the race. "In the end, P3, I'm happy, because the vehicle should be good in the race".
Ricciardo was quick to point to Hamilton s new engine as a factor even before its introduction was confirmed by Mercedes.More news: Australia out of World Cup as Carrillo and Guerrero strike for Peru
"We were relatively fast today, in the long runs we looked a bit up and down so definitely a bit of work to do tonight, but not a bad Friday", commented the Australian.
"I have no words to describe how I feel right now", Leclerc told reporters after reaching the final top 10 shootout for the first time.
The session was immediately red-flagged and Ericsson, 27, emerged unscathed from his charred Sauber.
There was gloom at McLaren, with last weekend's Le Mans 24 Hours victor and double world champion Fernando Alonso only 16th. Alonso's team-mate Stoffel Vandoorne finished in 13th.More news: New Zealand leader recovers with mac-n-cheese after birth
Brendon Hartley will start the race from last place after Toro Rosso had to change his Honda engine on Friday.