The native of Brandon, Manitoba, grew up in Vernon, B.C., and starred with the local Essos of the BCJHL before joining the Medicine Hat Tigers of the WCJHL for three years. In 1972-73 he played on the Tigers powerhouse when it reached the Memorial Cup finals. After scoring 118 points for Medicine Hat in 1973-74, he was chosen 104th overall in the amateur draft.

Johnstone started his pro career with the Michigan Stags of the WHA in 1974-75 but joined the Rangers the following year. After spending nearly two full seasons with the AHL's New Haven Nighthawks, Johnstone was ready for the NHL. In 1976-77 he was named to the AHL first all-star team after scoring 98 points.

As a rookie, Johnstone scored 26 points in 53 games for New York in 1977-78 and represented Canada at the Izvestia tournament in Moscow. He missed a fair bit of the 1978-79 season due to an injury but returned to score five goals in the playoffs as the Rangers reached the Stanley Cup finals for the first time in seven years. The feisty right-winger was particularly effective when he scored four goals in quarterfinals win over the Philadelphia Flyers.

Johnstone recorded consecutive 30-goal seasons in 1980-81 and 1981-82. In 1981 he was chosen to represent the Rangers in the NHL All-Star Game and set up Bill Barber with the first short-handed goal at the event in seven years. On June 13, 1983, Johnstone was part of a major deal with Detroit that saw him exchanged with Ron Duguay and Eddie Mio for Mike Blaisdell, Willie Huber and Mark Osborne. He battled injuries and reduced ice time with the Wings.

During the summers he returned to Vernon and was a catcher on the Enderby, B.C., team that won two provincial senior baseball titles. After playing parts of three seasons in Motown, Johnstone retired in 1987. He returned to Vernon and served as an assistant coach with the junior Lakers then served as the head coach when the team won two Centennial Cups. In 1992-93 he was hired as the coach of the ECHL's Johnstown Chiefs, an affiliate of the Boston Bruins.

Courtesy of the Hockey Hall of Fame