After missing the playoffs in the two previous seasons and needing to clear salary cap space to sign Alex Tanguay, the Flames dealt Regehr to the Buffalo Sabres on June 25, 2011. He was sent to Buffalo, along with Aleš Kotalík and a second round selection at the 2012 NHL Entry Draft in exchange for Paul Byron and Chris Butler. According to Flames' general manager Jay Feaster, the deal "surprised" Regehr, who initially was unsure he would waive his no-trade clause and agree to the deal. Regehr accepted the deal after speaking with Sabres' management.