Williamson was the first black person to serve on the Atlanta Board of Aldermen since Reconstruction, elected in 1965 and taking office in 1966.
[11] In 1964, he was the only black Georgia delegate to the Republican National Convention, where he fought a floor battle to nominate William Scranton.
[16] Williamson was sworn in on January 7, 1966, and appointed to seven committees: Police, Firemasters, Civil Defense, Park, Southeastern Fair, Insurance, and the Housing Authority Board.
"[1] As alderman, Williamson attended the Voter Education Project's first local government seminar at Clark College in 1967.
[21] Williamson served until 1981, when he was defeated by newcomer Myrtle Davis, in what the Atlanta Journal-Constitution later described as "personif[ying] the split between old-guard and new-guard black City Council members".