Ezra Matthew Miller was born in Wyckoff, New Jersey, to Marta (Koch), a modern dancer, and Robert S. Miller, who has worked at Workman Publishing and as former senior VP for Hyperion Books. He has two older sisters. Ezra is of Ashkenazi Jewish (father) and German-Dutch (mother) ancestry; he has described himself as Jewish and "spiritual".
As a child, Miller sang with the Metropolitan Opera and attended Rockland Country Day School and The Hudson School. His first feature film was the indie Afterschool (2008), and Miller subsequently appeared on the television series Californication (2007), Law & Order: Special Victims Unit (1999), and Royal Pains (2009), and in the films City Island (2009), Every Day (2010), Beware the Gonzo (2010), and Another Happy Day (2011).
Miller drew critical praise playing Kevin Khatchadourian, the homicidal son of Tilda Swinton's character, in the dramatic thriller We Need to Talk About Kevin (2011). He subsequently played Patrick in the well-received teen drama The Perks of Being a Wallflower (2012), opposite Logan Lerman and Emma Watson.
Ezra's upcoming roles include the period piece Madame Bovary (2014), Judd Apatow's comedy Trainwreck (2015), and the psychological thriller The Stanford Prison Experiment (2015). He has been cast as superhero The Flash in Untitled The Flash Film (2020), scheduled for release on March 23, 2018.