The deal was completed Saturday at the NHL draft.
The Flames sent Regehr, right-winger Ales Kotalik and their second-round draft pick in 2012 to the Sabres for defenceman Chris Butler and centre Paul Byron. Regehr, a 12-year veteran who has spent his entire NHL career with the Flames, waived his no-trade clause in order for the deal to be completed.
Regehr was an alternate captain for the Flames, scoring two goals and tallying 15 assists in each of the last two seasons. He'll bring some grit to the blue-line, with the Sabres aggressively trying to upgrade their roster under new ownership.