Newsom's office tells The Associated Press he will issue an executive order Wednesday granting a reprieve to every condemned inmate.
He's also withdrawing the lethal injection regulations that death penalty opponents have already tied up in court. And he's shuttering the execution chamber at San Quentin State Prison that has never been used. California hasn't executed anyone since 2006.
Voters have narrowly supported the death penalty, most recently in 2016 when they voted to speed up the process.
Newsom says he can act unilaterally because he's not commuting any sentences, which in many cases would require agreement from the state Supreme Court.
California currently has 737 inmates on death row, with the oldest case dating back to 1978.
The last California execution was Clarence Ray Allen on Jan. 17, 2006.
Since then, more than 70 other condemned inmates have died while waiting on death row of natural causes, suicide or other causes. Additional executions have not occurred because of numerous legal challenges to the state's method of lethal injection.
I have met with and am very supportive of Governor Newsom and his decision to help bring an end to the California Death Penalty. Racial bias and unfairness run deep throughout the justice system but especially when it comes to the death penalty.— Kim Kardashian West (@KimKardashian) March 13, 2019
Newsom's move is expected to generate significant political opposition.
The Los Angeles County Association of Deputy District Attorneys argued Newsom is doing an end-run around the will of California voters who have supported the death penalty in the past.
"The voters of the State of California support the death penalty," said association president Michele Hanisee. "That is powerfully demonstrated by their approval of Proposition 66 in 2016 to ensure the death penalty is implemented, and their rejection of measures to end the death penalty in 2016 and 2006. Governor Newsom, who supported the failed initiative to end the death penalty in 2006, is usurping the express will of California voters and substituting his personal preferences via this hasty and ill-considered moratorium on the death penalty."
The governor will hold a press conference Wednesday, March 13 at 10 a.m. in Sacramento.
The Associated Press contributed to this report.