Chicago needs to make deals for forwards Dominik Kubalik, who finished third in Calder Trophy voting, and Dylan Strome, and they do not have a frontline goalie under contract. Two-time Stanley Cup winner Corey Crawford is an unrestricted free agent.
Buying out the remaining two years of Maatta's contract was a legitimate option for Chicago, but they found a taker in the Kings.
"Olli is a well-rounded player who will fit well with our group of defensemen," Kings general manager Rob Blake said in a statement. "He is a young player that already has a lot of valuable NHL experience, including a pair of Stanley Cups, and we look forward to having him join our organization."
Maatta, 26, won those Cups with the Penguins before the Blackhawks acquired him in June 2019 in a deal that included Dominik Kahun.
Maatta was underwhelming during the regular season for Chicago, but he was arguably their best defenseman in the playoffs -- scoring three goals and six points, along with being a plus-7.
The Blackhawks get 23-year-old center Brad Morrison in the deal. He had 19 points in 17 games for the Fort Wayne Komets in the ECHL last season.