The longtime elected official and Marilyn Louise Flynn, 83, the former dean of the University of Southern California's School of Social Work, face federal bribery and conspiracy charges that stem from his time on the Los Angeles County Board of Supervisors.
The City Council voted 11-3 to suspend him.
The 20-count indictment accuses Ridley-Thomas, 66, of "supporting county contracts and lucrative contract amendments with the university" in exchange for benefits for a relative in 2017 and 2018, the Justice Department said.
Wednesday's motion was introduced by Council President Nury Martinez. Ridley-Thomas was not present at the meeting.
In a statement, he said he plans to clear his name.
"I am humbled by the support of my colleagues who did not rush to judgement and disappointed in those who did," he said. "Eleven members of this Council have stripped the constituents of the 10th District of their representation, of their voice and of their right to the services that they deserve. They have removed from action a member — and his team — who together are among the most productive and effective advocates on the crisis of homelessness."
On Friday, he said he does not plan to resign from office.
"Throughout my entire career, I have sought to act with the utmost ethical conviction," Ridley-Thomas wrote in a letter to the council.
"I will continue fighting to clear my name, and I remain confident that such will be the case," he added. "But in the interim, the council has disenfranchised the residents of the 10th District."
Michael Proctor, attorney for Ridley-Thomas, said many have rushed to judgment on his client.
"Today marks day one of due process for Mark Ridley-Thomas," Proctor said in a statement to Fox News. "While some have rushed to judgment, perhaps for political gain, we all win when we afford our brothers and sisters the constitutional entitlement to the presumption of innocence. Our lifelong public servant Mark Ridley-Thomas said today in court that he is innocent; I invite our community to breathe life into that right."
As a result of the suspension, Ridely-Thomas will not collect salary and benefits, Fox station KTTV-TV reported, citing Los Angeles Controller Ron Galperin,
"No one indicted for public corruption and suspended by the City Council should receive a taxpayer-funded salary," Galperin said.