First at General Wolfe junior high and then at Gordon Bell High School, Roy Williams became a force in youth basketball in Winnipeg. Bert Jones coached both at Gordon Bell and also a team called Lazy L in a YMCA league. Williams played for the two teams and both were provincial champs in 1943-44 and 1944-45. His next team was the University of Manitoba. For two seasons they were not in a league and played exhibition games against teams from neighbouring US colleges. In 1947-48, however, they won the new W.C.I.A.U. title downing the University of Saskatchewan.
He was also playing for Paulins, who won the Winnipeg Senior League championship and repeated in 1948-49. Williams' string of championships continued when the Manitoba Bisons won the senior crown, the Western Canadian title and were runners-up nationally in 1949-50. With a new team called the University of Manitoba Grads, it was a similar story. They were provincial champs in 1950-51 and also in 1951-52 when they went on to win the Western title and again lost in the National final to the Tillsonburg Livingstons.
In July of that year Williams and Carl Ridd were added to Canada's National team and played in the 15th Olympiad in Helsinki, Finland. At this time the Milwaukee Hawks of the NBA were interested in both Williams and Ridd, but they did not attend the pro camp.
After another provincial championship with Manitoba Grads, Williams was transferred to Chicago by his employer in the spring of 1953. He was again on a championship team in the Windy City in a commercial league. His job moved him back to Winnipeg in 1955 and he joined Kings Best late in the season to be a part of his last Manitoba championship. His employment entailed too much travelling to allow time for basketball. Williams was a league all-star from 1949 to 1953 and was named MVP twice. He gives credit to Acey Olson who came from Fargo to coach the Bisons and helped him develop a hook shot and to Jimmy Bulloch, the long-time Paulins player and coach. Roy Williams was inducted into the Manitoba Basketball Hall of Fame in 1983.
Roy Williams is also a member of the Manitoba Basketball Hall of Fame.