Gary Inness took the unusual route to the National Hockey League. He played collegiate hockey at McMaster University and at the University of Toronto, both of the Ontario University Athletic Association. In total he spent 5 years in the two Ontario colleges. Very few Canadian university students ever make it to the NHL.
Following his graduation in 1973, he jumped at an opportunity to take his chances with the pros when the Pittsburgh Penguins offered him a a contract. Inness impressed immediately. It was widely expected he'd be a minor league net keeper but he spent equal time in the big leagues. By 1974-75 he was the Pens starting goalie, with a 24-18-10 record with a 3.09 GAA and 2 shutouts.
The 1975-76 season saw Inness traded away after playing in 23 games with Pittsburgh. He went up state to Philadelphia where the Flyers were looking to shore up their goaltending depth with an injured Bernie Parent questionable at best.
Parent would become healthy soon enough and Inness would be the odd man out. He only got into two games the rest of that season, and in 1976-77 he saw action in only 210 minutes spread over 6 games.
Wanting a chance to play regularly, Gary signed on with the Indianapolis Racers of the World Hockey Association for the 1977-78 season. He spent a season and a half with the poor Racers team before signing with the NHL Washington Capitals. Only a few years earlier the Capitals had been the worst team in league history, but Inness helped to make them respectable, playing 37 games with a 14-14-8 record and a respectable 3.70 GAA.
Inness found himself as the odd man out in both 1979-80 and 1980-81, playing only 17 games in the league over that time span. He spent more time in the minors rather than the NHL.
Inness retired after the 1980-81 season. In total he appeared in 162 career NHL games with a record of 58-61-27 while posting two shutouts and a career goals-against average of 3.40. He also posted a record of 17-36-4 in 63 career WHA games with a 4.35 goals-against average
Inness later worked as a high school teacher at Barrie North Collegiate in Barrie, Ontario.