She got a best supporting actress gong for
her role in film drama Clouds of Sils Maria.
The big winner of the night was Timbuktu,
which won seven awards including best film
It depicts life in northern Mali under the
control of Islamist militants, and is competing
for best foreign film at Sunday's Oscars.
Accepting the prize, Stewart shouted "I love
you Juliette" in French to her co-star Juliette
She later paid tribute to French filmmakers.
"The reasons why people make films here in
France are very different from the reasons
why people make movies in Hollywood and I
prefer it here a little bit," she told Variety.
There also was recognition for another
American actor, Sean Penn, who got a
lifetime achievement award.
In his acceptance speech, Timbuktu director
Abderrahmane Sissako called France a
"magnificent country" for its response to the
deadly Islamist attacks last month.
"There is no clash of civilisations. There is a
meeting of civilisations," he said.