Hayden set out to become an actor when a chance encounter at the age of eight placed him in his first commercial, for Pringles. When he was thirteen, he had starring roles in several dramatic television series. His biggest break was a major part in the Fox Family Network's Higher Ground. On the series, Hayden showed off his acting talent as a teen who was sexually molested by his stepmother, and turns to drugs in despair. Later, he appeared in the television movie Trapped in a Purple Haze, where he co-starred with his friend Jonathan Jackson. Hayden also had a role in the film The Virgin Suicides.
On May 12, 2000, it was announced that Christensen would star as Anakin Skywalker in the prequels Star Wars: Episode II - Attack of the Clones and Star Wars: Episode III - Revenge of the Sith. The star was chosen by director George Lucas because he felt that Hayden had raw talent and good chemistry with actress Natalie Portman. Lucas stunned the movie world by picking the then-unknown actor after he had turned down such big names as Leonardo DiCaprio and Jonathan Jackson, as well as 400 other candidates.
His role as the troubled, misunderstood teenager Sam Monroe in Irwin Winkler's Life as a House won him 'Breakthrough Performance of the Year' from the National Board of Review. The film also placed him as a nominee for 'Best Supporting Actor' at both the Golden Globe and Screen Actors Guild Awards. Hayden then starred in Shattered Glass, quoted by some of the real Stephen Glass' colleagues as giving an eerie and uncanny portrayal.
When not working, he enjoys spending quality time with his family (such as big brother Tove), hanging out with his friends, and exploring other hobbies such as the blues, jazz and piano.