Nam was born on November 5, 1979, in Buenos Aires, Argentina, to Korean parents and moved to Sydney, Australia when he was six. 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.