Soros gave the organization "Stop the Republican Recall of Governor Newsom" $500,000 in a donation on Monday. Soros had previously given $500,000 to the Democratic group.
While Newsom has enjoyed a considerable fundraising advantage over his challengers, the race is shaping up to be closer than many had initially anticipated.
Soros' latest cash infusion into the race comes as conservative radio host Larry Elder is considered the leading challenger to replace Newsom in this month's recall election. If elected, Elder would be the first Black governor in California history.
Democrats have recently ramped up attacks on Elder, attempting to link his candidacy to former President Trump.
Newsom slammed Elder in a fundraising email last month, saying that Elder and Trump are one and the same.
"If this guy is governor during delta it would lead to extraordinary suffering," Newsom claimed in the email. "His anti-science approach would move our planet backward in the race against a changing climate. He would be a disaster for California."
The email also referred to Elder as "Larry Trump."
The California gubernatorial recall election is scheduled for Sept. 14.
Houston Keene is a reporter for Fox News Digital. You can find him on Twitter at @HoustonKeene.