The two will appear together in the Bay Area, where Harris grew up and began her political career as District Attorney in San Francisco.
She had been scheduled to campaign with Newsom last month, but remained in Washington after the Taliban rapidly took over Afghanistan.
Top Democrats across the country are lining up to urge support for Newsom in the election, which Republicans see as a rare opportunity to win the top office in a majority-Democratic state.
Sen. Elizabeth Warren of Massachusetts campaigned with Newsom in Los Angeles on Saturday, and President Biden has said he will travel to California before the election.
If a majority of California voters choose “yes” on the recall, then whichever of the 46 candidates on the ballot gets the most votes — even if far less than a majority — will become Governor.
Conservative radio talk show host Larry Elder is currently the front-runner with around 20% support according to polls.
All voters have been mailed ballots, and in-person voting begins Sept. 11 in San Diego County.