Johnston played in a total of 58 NHL games, scoring 20 goals and 32 points. But he was a scoring sensation in the minor leagues, making stops Providence, Kansas City and New Haven.
But it was in Washington state where he found his true hockey home. Starting in 1948 he starred for years with the Tacoma Rockets of the PCHL. His most productive professional season came in 1949-50 with the Tacoma Rockets, when he teamed on a line with Ronnie Rowe and Melvin Reed. Johnston had 46 goals and 90 points that year.
Johnston, who did serve in World War II with the Canadian Air Force (based primarily in Vancouver area base), moved to Spokane in 1953 and played as a playing-coach a couple more years. He would live in Spokane until his death in 2006, remaining active in hockey in the community. He worked for years as the Spokane Chiefs (WHL) statistician while also coaching and promoting the Spokane alumni hockey teams. He did all this while working for Wonder Bread, specializing in cake shipping.
Johnston also ran a hockey school in Nanaimo, British Columbia for a period of time.