"California is the state where anything is possible with hard work and determination, but our future depends on our willingness to face our biggest challenges," he said in his announcement video posted on social media Tuesday. "I believe we need a problem solver to lead our state. That's why I'm running for governor."
Villaraigosa, 71, ran for governor in 2018 but finished third in the primary.
Several other Democrats have already announced their candidacy, including Lt. Gov. Eleni Kounalakis, Sen. Toni Atkins, State Superintendent Tony Thurmond and former State Controller Betty Yee.
Gov. Gavin Newsom is term-limited and cannot run for reelection.
This is a developing story. This article will continue to be updated as more information becomes available.