Innisfail winger represented Queensland in 1964 and 1967 in between which he played a season with Halifax (1964-65). Gaining selection in Australia's World Cup squad in 1968, Williamson scored two tries in the final against France. Rated as having the surest pair of hands in top-class football, he came to Newtown in 1969 after Canterbury baulked at paying the $7,000 transfer fee. A big, bustling winger whose career got better as he got older, Williamson played in his second World Cup competition in 1970 and was a try-scorer in Australia's spiteful 12-7 final win over Great Britain at Leeds. The following year he made his Test debut in the 24-3 loss to NZ at Carlaw Park. Williamson was in great form with 1973 club champions Newtown and, at age 29, toured with the Kangaroos. Williamson played in the two Tests against Great Britain and another against France. In 1974 he was called into the deciding Test against the visiting Lions and scored a vital try in Australia's 22-18 win. After his retirement Williamson coached schoolboy teams at St Gregory's Campbelltown and St Augustine's, in Cairns.