Johnston had spent the previous two seasons playing for the Johnstown Jets of the EHL and the Tulsa Oilers of the Central Hockey League (CHL).
With his increased value, Johnston was traded by Los Angeles to the Detroit Red Wings along with Dale Rolfe and Gary Croteau for Garry Monahan, Brian Gibbons and Matt Ravlich on February 20, 1970.
137–138, Troy Treasure, Balboa Press), when the Michigan franchise moved to Baltimore to be operated by the WHA, Johnston claimed the league failed to properly abide by the terms of his contract.
According to published reports, Johnston's agent Bob Wolfe told Baltimore media his client had effectively bought out the remainder of his contract for what he was owed for the rest of the season.
The Kansas City Scouts acquired Johnston on March 1, 1975, in exchange for an undetermined amount of cash to add muscle and organization to their young defence.