Riley appeared as a disguise used by Tom Hardy's character in Inception (2010). Also in 2010, The Summer House was released, which starred Riley in the lead role. By the end of the first day of release, it was the number one film on iTunes worldwide and dominated that position for several days. She also played Mary Bennet in the 2005 version of Pride and Prejudice, acted in the role of Marianne in 2009's The Boat That Rocked, and starred in the 2007 film St Trinian's and its 2009 sequel St Trinian's: The Legend of Fritton's Gold. She also appeared in White Frog.
She was featured on the March 2010 cover of Esquire.