DeBrincat's contract runs through the 2022-23 season with an average annual value of $6,400,000.
The Blackhawks drafted DeBrincat, 21, in the second round of the 2016 NHL Draft. Last season, DeBrincat scored 41 goals and had 35 assists.
The Blackhawks announced the deal one day before they open the season with the Philadelphia Flyers in the Czech Republic.