The 33-year-old Leighton provides some organizational depth behind starter Corey Crawford and backup Antti Raanta. Barring injury, he could spend much of the year with Chicago's AHL affiliate in Rockford.
Leighton was drafted by Chicago in the sixth round of the 1999 draft and made his NHL debut with the Blackhawks in January 2003. He has a 35-41-14 record with a 2.97 goals-against average in parts of eight seasons with Chicago, Nashville, Philadelphia and Carolina.
Leighton was in goal for Philadelphia when Patrick Kane scored in overtime in Game 6 of the 2010 Stanley Cup finals, giving the Blackhawks the title.
The Blackhawks announced the contract on Monday.