General manager Don Maloney announced the deal Monday, but didn't disclose financial terms.
The 25-year-old Schlemko has been sidelined since Feb. 4 with a shoulder injury. He has two assists in nine games this season and ranks second on the team with 26 blocked shots.
Schlemko originally was signed by the Coyotes as a free agent in 2007.
In 118 career NHL games, all with Phoenix, Schlemko has six goals, 27 assists and 44 penalty minutes.