Beirne, whose December departure is the latest in a string of Maple Leaf Sports & Entertainment moves, says he leaves the team with plenty of good memories.
"This Saturday's TFC match will be my last with the club," Beirne tweeted Thursday. "Thank you for 7 seasons of awesome moments! So proud to have been a part of it!"
Toronto wraps up its season Saturday against the visiting Montreal Impact.
Beirne, 47, was offered another position outside of soccer at Maple Leaf Sports & Entertainment but declined.
"The organization structure changed with the new leadership," Beirne, choosing his words carefully, said in an interview.
He already has a new job lined up, although he declined to detail his next challenge.
MLSE president and CEO Tim Leiweke has rung in the changes since taking over MLSE this summer.
Toronto FC president and Kevin Payne was fired last month, with Tim Bezbatchenko taking over as GM.
Leiweke, the man who brought David Beckham to MLS, has been particularly hands-on with TFC since taking charge. Leiweke, Bezbatchenko and manager Ryan Nelsen recently returned from a scouting trip to Europe in search of marquee talent.
MLSE revamped its senior management in July and COO Tom Anselmi stepped down last month.
Asked if he would have stayed with the soccer team if he had his druthers, Beirne replied diplomatically: "I will always be part of TFC."
While Toronto has been a model franchise in many regards off the field, its lack of success on the pitch has been galling — and fan support has suffered as a result.
The 5-17-11 team has missed the playoffs for the seventh straight year. The team has averaged 18,439 at BMO Field, which ranks 10th in the league this season, and attendance plummeted to 12,627 in a rain-drenched loss to Sporting Kansas City last month.
Beirne joined MLSE in 1994 and became director of business operations for TFC in May 2006, switching from his job in charge of the Leafs' and Raptors' tickets operations.
Despite the continued struggles on the pitch, Beirne sees light at the end of the Toronto FC tunnel.
"Between Tim and Ryan, I think the football side of things is in really good hands," he said.
He pointed to past lack of consistency in coaches and players.
"That's not a shot at anybody involved along the way. It's just been our reality for seven years. So as a fan of TFC, I'm very optimistic for the future."
As vice-president of business operations, Beirne essentially was in charge of everything at the club outside the pitch.
He makes no excuses, but sees more positives than negatives at the club.
"We've made our bed, when you're talking about our reputation or how fans perceive us," he said. "However, I'm enormously proud, of not only what happens at BMO Field on Saturdays in the summer but what's happening up at the KIA Training Ground, what's happening with our the academy, how the other teams in Canada have followed suit.
"I think we're in the middle of a sea change and all positive for the game in Canada," he added. "I'm just enormously proud to have been a small part of it."
Beirne was a popular figure among many TFC supporters, who saw the same kind of enthusiasm for the club as they had.
"This is my baby and the baby of a handful of us here," he said. "My wife reminded me this morning if you love something, you've got to set it free.
"So I am looking forward to taking in the games from the stands. I still have season tickets and I won't be leaving any time soon."