Williamson was a well-performed professional runner.
Having been banned from professional foot-running for "running dead", he turned his efforts towards acting as a radio commentator of Australian rules football matches in the Victorian Football League with 3AK and 3AW, Williamson joined HSV-7 in 1959 as part of Seven's VFL coverage.
Key moments in Williamson's commentary career include the 1966 Grand Final where St Kilda won their first premiership as well as the 1970 VFL Grand Final where Williamson called the now immortal "Jesaulenko, you beauty!", one of the most famous quotes in the history of Australian rules. The words were part of numerous advertising campaigns, including one for Carlton Draught, as well as a 2006 Toyota Memorable Moments campaign featuring Alex Jesaulenko himself. He presented the premiership medallions to Essendon in 1993.
As well as commentating, Williamson was involved with general announcing duties at both 3AK and 3AW. At HSV-7 he compared a number of variety and quiz shows, the most notable being Tell the Truth and The Penthouse Club. The latter was co-hosted by Mary Hardy who later compared the show with others, including Bill Collins and Ernie Sigley. "The Penthouse Club" provided variety, including live acts, in-between broadcasts of trotting races. It also introduced to Melbourne, the live broadcasting of the Tattslotto draw.
Williamson retired in 1977 and was awarded an OAM for his charity work.