The deal was completed Saturday at the NHL draft.
The Flames sent Regehr, right wing Ales Kotalik and their second-round draft pick in 2012 to the Sabres for defenseman Chris Butler and center Paul Byron. Regehr, a 12-year veteran who has spent his entire NHL career with the Flames, waived his no-trade rights 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 thet last two seasons. He'll bring some grit to the blue line, with the Sabres aggressively trying to upgrade their roster under new ownership.