Sulzer's deal is worth $725,000, a source told ESPN.com's Pierre LeBrun.
Sulzer played in 15 games with Buffalo last season after being acquired from the Vancouver Canucks, along with forward Cody Hodgson on Feb. 27. Sulzer, who had three goals and eight points with the Sabres, also appeared in 12 games with the Canucks last season, collecting one assist.
In 89 career NHL games, Sulzer has four goals and 16 points. He would have become an unrestricted free agent on July 1.
Information from The Associated Press was used in this report.