Before his Hollywood success, he travelled to New York City to pursue his acting career. His first few nights he slept in Central Park and then found jobs working as a waiter and bartender. His breakthrough role came in his performance of Roy in The Perfect Score (2004). He had a small role in the 2005 film The Sisterhood of the Traveling Pants as Brian McBrian, a hardcore gamer. He played Brian again in The Sisterhood of the Traveling Pants 2; in the sequel, his character has a larger role. Nam also made an appearance in The Fast and the Furious: Tokyo Drift (2006) as Morimoto. In 2016, he joined the cast of the HBO series Westworld.