M-222 is the current designation of a state trunkline highway in Allegan County of the US state of Michigan. It runs between the city of Allegan, where it connects with M-40/M-89, and the US Highway 131 (US 131) freeway near Martin. The highway runs along a series of streets in Allegan and through rural farm fields and woods between the two communities along 116th Avenue. The roadway was a state highway back in 1919 when the system was initially signed. It was assigned as part of M-89 and M-40 before being given its own number, M-118. That designation was applied to the highway until 1988 when that was retired in favor of the current M-222.