The 'East A' actress had reportedly been Sony Pictures favourite for romantic lead Mary Jane Watson but it has now emerged she will be portraying the other love interest of the titular superhero and his Alter Ego Peter Parker - to be played by Andrew Garfield - instead.
Sony president Matt Tolmach said: "It's been an incredible Journey for us to watch Emma's star rise as an actress. 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."
Director Marc Webb added: "The chemistry between Andrew and Emma was stunning and made Emma the clear choice. 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."
Emma is expected to have to lose her red hair in favour of the bleached-blonde style the character usually sports.
Stars including 'Glee' actress Dianna Agron and 'Alice in Wonderland' beauty Mia Wasikowska are now reportedly being considered for the role of Mary Jane, who was most recently played by Kirsten Dunst opposite Tobey Maguire as Spider-Man.
The new storyline is expected to follow these much-loved characters back at high school, as Peter comes to terms with his powers.
'Spider-Man 4' is expected to be out in cinemas in July next year.