The same year, Oh was cast on the hit ABC medical series Grey's Anatomy as Cristina Yang.Oh's long-running role on the show earned her both a 2005 Golden Globe Award for Best Supporting Actress in a Series and a 2006 Screen Actors Guild Award for Outstanding Performance by a Female Actor in a Drama Series.She also had a supporting role on the HBO original drama series Arliss.She has played notable roles in the feature films Bean (1997), Last Night (1998), The Princess Diaries (2001), Under the Tuscan Sun (2003), Sideways (2004), Wilby Wonderful (2004), Sorry, Haters (2005), Hard Candy (2005), The Night Listener (2006), Blindness (2008), Rabbit Hole (2010), Tammy (2014), and Catfight (2016).Oh received critical acclaim for her six seasons as Rita Wu, the assistant to the president of a major sports agency, on the HBO series Arliss.She received an NAACP Image Award for Best Supporting Actress in a Comedy Series and a Cable Ace award for Best Actress in a Comedy for her work on Arliss.
She also has done a few voice roles in animation, including a few guest appearances in American Dragon: Jake Long, the voice of Princess Ting-Ting in Mulan II and the voice of Doofah in The Land Before Time XIII: The Wisdom of Friends.
She has also starred in the Asian Canadian films Double Happiness (1994), The Diary of Evelyn Lau (1994), and Long Life, Happiness & Prosperity (2002), the former films of which won her the Genie Award for Best Performance by an Actress in a Leading Role and the Gemini Award for Best Performance by an Actress in a Leading Role in a Dramatic Program or Mini-Series, respectively.
Later, at Sir Robert Borden High School, she founded the Environmental club BASE (Borden Active Students for the Environment), leading a campaign against the use of styrofoam cups.
While at Sir Robert Borden High School, she was Student Council President.
She also played the flute and continued both her ballet training and acting studies; however, she knew that she "was not good enough to be a professional dancer" and eventually focused solely on acting.