Lehner finished in third place in Vezina Trophy voting as the league's top goaltender this past season. He posted a .930 save percentage and a 2.13 goals-against average in 46 games played with the New York Islanders.
Lehner, along with former teammate Thomas Greiss, took home the Jennings Trophy for allowing the fewest goals in the league. He also won the Bill Masterton Trophy for his remarkable season after a well-documented battle with mental illness and alcoholism.
On June 23, Lehner said he had "no plans" to talk to other teams during the free-agent negotiation period as he was intent on returning to Long Island.
The Blackhawks now have just over $1 million in cap space remaining with 10 forwards, eight defensemen, and three goalies signed, according to CapFriendly. The club has two remaining RFAs: Brendan Perlini and Victor Ejdsell.
Corey Crawford, who backstopped Chicago to two Stanley Cups, has one year remaining on his deal with a $6-million cap hit. Concussions have forced him to miss significant time over the past two seasons.