As like most young talented hockey stars in Winnipeg during the 1940s, Al Buchanan played for the Winnipeg Monarchs of the Manitoba Junior Hockey League. During his rookie year in 1944-45, Buchanan played in six regular-season games, scoring five goals and ten points. He then was part of the Monarch team which went on to represent the MJHL at the Memorial Cup, eventually won the Toronto St. Michael's Majors. The following year Buchanan was named team captain and the Monarchs again advanced to the Memorial Cup, this time coming away as champions for the 1945-46 season. After one more season in Winnipeg, Buchanan joined the Toronto Marlboros of the OHA Junior league in 1947-48.
Buchanan's pro career began in 1948-48, playing three games with the Toronto Maple Leafs, where he picked up one assist. The balance of his season was spent in Toronto as a member of the senior Marlboros team. Buchanan was called up for one game with the Maple Leafs in 1949-50, which turned out to be his final game in the NHL.
Buchanan continued to play professional hockey for another five years, with the Marlboros, the St. John Beavers of the MMHL, the Kitchener Dutchmen, Hamilton Dutchmen and finally the Niagara Falls Cataracts, all of the OHA senior league.