A judge on Friday approved
Jenner, 65, sought the change "to better match my identity," according to court filings she submitted earlier this month.
L.A. County Superior Court Judge Gerald Rosenberg granted the petition during a brief hearing. Jenner did not attend but was represented by two lawyers.
The approval means Jenner's new name will be Caitlyn Marie Jenner, replacing her birth name of William Bruce Jenner. She will now be able to get documents -- including a driver's license and Social Security card -- that conform to her new identity.
Jenner publicly transitioned to a woman in recent months after revealing her intentions to journalist Diane Sawyer in a televised special and debuting her new name and look on the cover of Vanity Fair magazine.
Some details that accompanied her petition to legally change her name and gender were redacted after Jenner cited privacy concerns and threats she says she has received during her transition.
"Although public support for my transition has been overwhelmingly supportive, I am also receiving unwelcome negative attention from private citizens, including threats of bodily harm," Jenner wrote in a sworn declaration.
A background check is needed to legally change one's name, and Jenner also had to submit a medical declaration, both of which were filed under seal.
Jenner won a gold medal in the men's decathlon at the 1976 Olympics and was married to Kris Jenner, mother to the Kardashian sisters, for more than 20 years. The pair had two daughters together, Kendall and Kylie Jenner.
Caitlyn Jenner appeared on their reality series, "Keeping Up With the Kardashians," and has documented her transition on her own TV series, "I Am Cait."
L.A. County prosecutors are still considering whether to file a criminal case against Jenner over a February traffic collision on the Pacific Coast Highway that left a woman dead.
Jenner's sport utility vehicle crashed into two cars Feb. 7, pushing a car driven by Kim Howe into oncoming traffic. Howe, 69, died after her vehicle was struck by a Hummer, and her stepchildren are suing Jenner for wrongful death.
Sheriff's investigators determined Jenner was traveling at an unsafe speed for the road conditions, and there was enough evidence to support a charge of vehicular manslaughter, the department said last month.