McLellan, 51, will be taking over for interim coach Willie Desjardins. The Kings fired former coach John Stevens last November.
The Kings have made the playoffs only twice since winning the 2014 Stanley Cup and were eliminated in the first round on both occasions. They went 31-42-9 this past season, good for last place in the Pacific Division and a Western Conference-low 71 points.
The Kings will pick fifth in the 2019 NHL draft after dropping three spots in the lottery.
While the franchise enjoyed an extended run of success, odds are this is the beginning of a full-scale rebuild rather than a reload. The Kings are in need of an influx of young talent after going for broke to win a pair of Stanley Cups, and their fans have already moved on to looking at who might be available at No. 5.
McLellan made the playoffs in each of his first six seasons as an NHL coach but has missed the postseason four of his past five years.