"They're both thrilled," Johansson's rep Marcel Pariseau told People.

Reynolds, 31, who is currently filming The Proposal in Boston with Sandra Bullock, was reported to have just recently popped the question to Johansson. The couple have not set a wedding date.

Johansson, 23, the star of Girl with a Pearl Earring and The Nanny Diaries, was photographed wearing a diamond ring at Monday night's Metropolitan Museum Costume Institute Gala in New York.

She is due to release her debut album, Anywhere I Lay My Head on May 20 with cover versions of Tom Waits songs and vocals from David Bowie.

Reynolds, who has starred in movies like Definitely, Maybe and Smokin' Aces, was once engaged to Canadian singer Alanis Morissette.