The announcement was made Tuesday by Amy Pascal, co-chairman of Sony Pictures Entertainment, and Matt Tolmach, president of Columbia Pictures.
The film, to be directed by Marc Webb from a screenplay by James Vanderbilt and produced by Avi Arad and Laura Ziskin, will begin production in December and will be released in theaters nationwide in 3D July 3, 2012.
Stone's film credits include "Easy A," "Superbad," "The House Bunny" and "Zombieland." Garfield is one of the stars of "The Social Network."
"It's been an incredible journey for us to watch Emma's star rise as an actress," Tolmach said in a statement. "She is extraordinarily talented and has a very special on-screen spark that is perfect for this role. Given her history with the studio, casting her in one of our most important franchises is a real thrill."
"The chemistry between Andrew and Emma was stunning and made Emma the clear choice," Webb added. "At the heart of the story of Peter Parker is not only the amazing Spider-Man, but also an ordinary teenager who is wondering what he has to do to get the girl. Andrew and Emma will bring everything audiences expect to these roles, but also make them their own. Much to my surprise, it was fun to find out that our choice for Gwen is also a natural blonde."