Miller's start in film began in 2008 with Antonio Campos' Afterschool, in which he played a teenager at a boarding school who accidentally films the drug-related deaths of two classmates, and is then asked to put together a memorial video. He appeared in City Island (2009), with Andy García, Julianna Margulies, and Steven Strait, and co-starred in Beware the Gonzo and Every Day, both of which premiered at the Tribeca Film Festival. Miller next appeared in the BBC Films film We Need to Talk About Kevin (2011), alongside Tilda Swinton and John C. Reilly, which was adapted and directed by Lynne Ramsay from American author Lionel Shriver's 2003 novel of the same name. The film became a Cannes Film Festival sensation, receiving critical acclaim. Miller played Damien on the Showtime hit comedy series Californication. He appeared on Royal Pains as Tucker Bryant for two seasons. In the 2012 film adaptation of the novel The Perks of Being a Wallflower Miller portrayed Patrick, alongside Logan Lerman and Emma Watson.