Harris, who was the Eagles' first-round draft pick in 1971 and played three seasons with the team before going on to also play for the Chicago Bears and Seattle Seahawks, was the defensive line coach for the Blue Bombers.
"This has struck our entire organization from the top down," Blue Bombers President Jim Bell said. "We are all in a state of shock, and first and foremost would like to express our deepest sympathies to his family.
"The Winnipeg football club has lost not only a great coach, but an even better man."
The club didn't release any additional details about the death.
Harris, who joined the Blue Bombers in 2006, previously coached for the Ottawa Renegades and the BC Lions in the CFL.
Millions of Getty images now available for free via embed tool
Aaron Carter is still in love with Hilary Duff