Watson began his career in Scotland playing for Ayr United and Vale of Leven F.C.
In the spring of 1928, he signed with the Bethlehem Steel of the American Soccer League at the end of the 1927-1928 season as a replacement for injured Bob MacGregor.
By that time, the ASL was on its last legs and Alex McNab, New Bedford's captain accepted an offer to move west to SBF where he became a player-coach.
The St. Louis teams relied on the sponsorship of local businesses to the extent that they changed names to match their sponsors.
Watson remained with the club through these name changes, winning the 1935 National Challenge Cup and finishing runner up in 1936 and 1937.