Kassian, 26, appeared in 79 games with the Oilers last season, finishing with 24 points (seven goals, 17 assists) and 101 penalty minutes. He added three goals and 27 penalty minutes in 13 playoff games.
The 6-foot-3, 207-pound winger has appeared in 313 NHL games with Buffalo, Vancouver and Edmonton, with 98 points (45 goals, 53 assists) and 522 penalty minutes. He has also played in 21 playoff games, and has three goals and 33 penalty minutes.
The Windsor, Ontario, native represented Canada most recently at the 2011 world championship. He has also played at the 2009 under-18 world championship and the world under-17 challenge.
Kassian was selected by Buffalo in the first round, 13th overall, in the 2009 draft.