Dauriac, who co-owns an independent advertising agency, proposed to 'The Matchpoint' star.
Her representative has confirmed the news, but did not disclose when it occurred, reported CNN.
"They haven't chosen a date for the wedding," she said.
Johansson, 28, was spotted wearing the diamond stunner earlier this week while promoting her new sci-fi movie 'Under the Skin' at the Venice International Film Festival.
The actress was previously married to Ryan Reynolds but they divorced in 2011. Reynolds later married Blake Lively.