The actress, 21, was selected after reportedly displaying an instant connection to Andrew Garfield, 27, who will play Parker/Spider-Man. "The chemistry between Andrew and Emma was stunning and made Emma the clear choice," says the director, Marc Webb.
The new Spider-Man movie will begin production in December and hit theaters in 3-D on July 3, 2012.
Although she's known as a redhead, Stone will presumably be reverting to her natural hair color to play Stacy. "Much to my surprise, it was fun to find out that our choice for Gwen – Emma – is also a natural blonde," says Webb.
Stone got her big break in 2007's Superbad, playing Jonah Hill's girlfriend Jules. She is currently starring in the comedy Easy A and will appear in the upcoming Crazy, Stupid, Love with Steve Carell and Ryan Gosling.
"It's been an incredible journey for us to watch Emma's star rise as an actress," says Sony Pictures Entertainment co-chairman Matt Tolmach. "She is extraordinarily talented and has a very special on-screen spark that is perfect for this role."