Rumours that the Charlie's Angels star's boyfriend had proposed began to swirl last week (ends08Jan12) and the actress confirmed the speculation by releasing a snap of her showing off her engagement ring over the weekend (07-08Jan12).
The marriage will be Barrymore's third, and the star has spoken of her contentment after reaching a more "stable" time in her life.
She tells InStyle magazine, "It's really positive. I'm super happy. As I've gotten older, I've really wanted to find more balance and calm."
And the beauty reveals her art consultant beau has gone down a storm with friends such as Cameron Diaz, adding, "It's just the best! We go on group trips and spend holidays together. There's a lot of love."
Barrymore has been married twice before - to bar owner Jeremy Thomas in 1994 and comedian Tom Green in 2001. Both marriages lasted less than five months. She was dating Justin Long before Kopelman.