Born to Korean parents in the Ottawa suburb of Nepean, Ontario, Canada. Her father and mother, who were married in Seoul, South Korea, both attended graduate school at the University of Toronto. She began her career as a ballet dancer and eventually studied drama at the National Theatre School in Montreal. She then starred in a London (Ontario) stage production of David Mamet's "Oleanna" and appeared as the title character in the Canadian television production The Diary of Evelyn Lau, beating out over 1,000 applicants. Her list of awards includes the FIPA d'Or for Best Actress at the 1994 Festival International de Programmes Audiovisuels at Cannes, France, two Genie Awards (the Canadian Oscar), a Cable Ace Award, a Theatre World Award and a Screen Actors Guild Award. In 2003, she married writer-director Alexander Payne and their first film together was the Oscar-winning Sideways.
Was a member of a National Champion Canadian Improv Team at The Canadian Improv Games in the late nineties. When asked who her favorite rock-star is, she answered Wayne Coyne (lead singer of The Flaming Lips), the reason being he looks enough like her husband, Alexander Payne, for her to pretend her fantasy about being married to a rock-star is true! Attended Sir Robert Borden High School in Nepean, Ontario. She has played a pregnant woman in two films: in Under the Tuscan Sun with Diane Lane, and in Cake with Heather Graham. At the 2005 SAG awards, Sandra Oh presented the Actor for actress in a TV comedy - Teri Hatcher won the award. A year later at the 2006 Golden Globes, Hatcher presented the award for best supporting actress on TV - Oh won that award and later said it was good to see her again! In Under the Tuscan Sun, her girlfriend was portrayed by Kate Walsh, who went on to costar with her in Grey's Anatomy. Coincidentally, Kate also played a doctor in the film. She has the distinction of playing two characters that co-exist in Armistead Maupin's fictional universe. In Further Tales of the City, she portrayed a bitchy newswoman who complicated "DeDe Day"'s mission to protect her twins, Anna and Edgar. In The Night Listener, Oh portrays an adult "Anna Day". Attended the National Theatre School in Montreal, Quebec. In Dancing at the Blue Iguana, Sandra's character came from Seattle, Washington to work in Southern California. In Grey's Anatomy, her character came from Southern California to work in Seattle. She loves Spain and especially the city of Barcelona.