Leddy had seven goals and 24 assists in 82 games for Chicago last season. Leddy, who turns 24 in March, has played in 258 regular-season games and made 54 postseason appearances.
The Blackhawks also sent goaltender Kent Simpson to New York on Saturday for defensemen T.J. Brennan and Ville Pokka and the rights to restricted free-agent goaltender Anders Nilsson. Brennan and Pokka were assigned to Rockford of the American Hockey League.
Leddy was selected by Minnesota in the first round of the 2009 draft and traded to Chicago in February 2010.