As sources said, Greenwald, 36, popped the question to the Oscar-winning actress, 26, during a trip to Tokyo in March this year. Recently, Larson was spotted wearing her new engagement ring while she was hosting American TV show "Saturday Night Live" on May 7.
The couple have been dating on and off for several years and Larson gave her first public shout-out to Greenwald in 2013 during her winner’s speech for Best Actress for "Short Term 12" at the Gotham Independent Film Awards.