Cowan was born in Paisley and began his professional career with St Mirren before moving to Morton in 1944.
He remained at Cappielow for nine years, playing in the 1948 Scottish Cup Final defeat to Rangers.
During his time at Morton he won all of his 25 Scotland caps, making his debut against Belgium in April 1948.
He played in the 1949 and 1951 wins against England at Wembley, results which ultimately won Scotland the 1948–49 and 1950-51 British Home Championships.
He returned to Scotland two years later with Third Lanark and played for a season at Cathkin Park before retiring.