Glasgow born outside left Charlie Johnston began his football career with Blantyre Victoria, from where he was signed by Scottish First Division club Motherwell in 1932. Johnston made his Scottish League debut as a much depleted Motherwell side played host to Clyde at Fir Park as Clyde won 2-1 in December 1933. The next time he featured he netted as the side defeated Falkirk 3-1 at Brockville immediately after New Year. His third and final appearance of the season saw him line up against Queen of the South but once again the side slipped up as The Doonhamers won 2-1. He only made 3 more appearances for The Steelmen over the following seasons before signing for Second Division club Doncaster Rovers in 1935, making his Football League debut at Bury in January 1936.
After Doncaster’s relegation in May 1937, Johnston joined Third Division (South) club Mansfield Town after 3 goals in 37 appearances for Rovers, and he missed only 6 matches for The Stags during their 1937-38 campaign, scoring 5 goals in 40 appearances before returning to Scotland in the 1938 close season to join Dunfermline Athletic. He scored 10 goals in 29 appearances for The Pars but his career was then interrupted by the outbreak of the Second World War in September 1939, and in 1940 he joined Glasgow Rangers for £350, where he played six seasons of wartime football, scoring 68 goals in 206 appearances for Rangers.
As a result of his good form with The Gers, Johnston was selected to play for Scotland in an unofficial wartime international against England at Wembley in 1942. When peacetime football resumed in 1946, Johnston joined Queen of the South, and enjoyed seven seasons with the Palmerston Park club, scoring 30 goals in 165 appearances for Queens before his retirement in 1953. While at Queen’s he won the 1951 Scottish B Division Championship and played in two major domestic cup semi-finals during one of their strongest periods.