He was born in New York City and is perhaps best known for Walk the Line which he co-wrote and directed. Working consistently as a feature writer and director since 1995, when his first feature, the independent film Heavy, won the best directing prize at Sundance.

Mangold subsequently wrote and directed Cop Land starring Sylvester Stallone, Robert DeNiro, Harvey Keitel and Ray Liotta; Girl, Interrupted, which won the Best Supporting Actress Oscar in 1999 for Angelina Jolie; "Kate and Leopold", starring Meg Ryan and Hugh Jackman for which Jackman was nominated for best actor in a musical or comedy in 2001, and the 2003 thriller Identity which starred John Cusack.

In 2005 he co-wrote and directed Walk the Line, a film about the young life of singer-songwriter Johnny Cash and his relationship with June Carter Cash. It stars Joaquin Phoenix and Reese Witherspoon and was released on November 18, 2005. It was nominated for five Oscars and Witherspoon won Best Actress for her performance as June Carter Cash. His next film, to be released in October 2007, is a Western, "3:10 to Yuma" starring Russell Crowe and Christian Bale.

After high school, Mangold was accepted into the California Institute of the Arts film/video program. While there, he mentored under Alexander Mackendrick. During his third year, Mackendrick suggested Mangold study at CalArts School of Theater as an actor alongside with his regular film studies. One of his classmates was Don Cheadle.

Based on the response to his short films, in 1985 Mangold got a fast start as a graduate out of CalArts, securing a writer/director deal (at age 21) at Disney. Mangold grew disillusioned at the studio. He wrote a television movie and the animated feature "Oliver and Company". A few years later, Mangold decided to re-establish himself in New York and applied to Columbia University's film school, where he graduated with an MFA in film. While there, he studied under Miloš Forman and developed both "Heavy" and "Cop Land".

During the filming and production of Cop Land, Mangold met his partner and wife, producer, Cathy Konrad.

Mangold also appeared as an actor in The Sweetest Thing as a doctor and love interest to Christina Applegate as well as in his own "Kate and Leopold" playing a movie director.