Indicted on nineteen criminal counts in 2021, Ridley-Thomas was found guilty of seven of the charges on March 30, 2023, including conspiracy, bribery, honest services mail fraud, and four counts of honest services wire fraud "extracting special benefits for his son from USC while voting in support of motions and a contract sought by the university.

[3] After a brief stint as a high-school teacher, Ridley-Thomas was executive director of the Southern Christian Leadership Conference of Greater Los Angeles (1981–1991).

[7] In the Assembly, Ridley-Thomas served as chair of the Democratic caucus and was a major proponent of efforts to encourage an NFL team to move to the Los Angeles Memorial Coliseum, which is located in his district.

In the Assembly, Ridley-Thomas, as chairman of the Select Committee on the Los Angeles County Health Care Crisis, was a leader in addressing the problems facing the hospitals and health care system of Los Angeles, sponsoring a bill that would create the Office of Inspector General in an effort to detect and prevent fraud, waste and abuse in government agencies.

[11] He was also one of the lawmakers who called for tourists to boycott the LAX Hilton because of its efforts to overturn a city ordinance that would grant a living wage to airport-area hotel workers.

His most formidable opponent was former LAPD police chief Bernard C. Parks, the member of the Los Angeles City Council who replaced Ridley-Thomas when he was elected to the State Assembly.

[24] In 2009 Ridley-Thomas was criticized, most notably by radio talk show hosts John and Ken, for his proposal and personal defense of plans to remodel his office through the spending of $707,000 in discretionary funds.

Amidst the state budget crisis in California, John and Ken criticized MRT on December 21, 2009, saying that the discretionary funds, "[are] our money and we say no.

Sony's donation was three times larger than for any other California candidate or committee that year, and was understood to be in support of the school board campaign of a Ridley-Thomas protégé.

[32] During his 2020 race for Los Angeles City Council, environmental activists criticized Ridley-Thomas for his acceptance of donations from the fossil fuel industry.

[33] While the other four candidates in the race called for the city to phase out urban oil drilling within 2,500 feet of homes and schools, Ridley-Thomas has opposed the idea of a citywide buffer.

[33] On October 13, 2021, the United States District Court for the Central District of California announced that a federal grand jury had indicted Ridley-Thomas and Flynn for "a bribery scheme in which his son received substantial benefits from USC in exchange for Ridley-Thomas supporting county contracts and lucrative contract amendments with the university while he served on the Los Angeles County Board of Supervisors.