Forward prospect Brad Morrison was sent back to Chicago in the trade. The Blackhawks will retain $750,108 of Maatta's $4,083,333 salary in 2020-21 and 2021-22.
Maatta had 17 points in 65 games while averaging over 18 minutes of ice time with the Blackhawks last season. He also had a team-leading plus-seven rating in nine playoff games, with six points.
"Olli is a well-rounded player who will fit well with our group of defensemen," Kings vice president and 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."
Morrison appeared in 17 games with the ECHL's Fort Wayne Komets last season, scoring six goals and 19 points.