Unadilla was formed by an act of the Legislative Council of the Territory of Michigan on March 26, 1835, and initially included what is now Iosco Township to the north and a portion of Lyndon township in Washtenaw County on the south.

[citation needed] The first land purchase in the township was recorded on June 20, 1833, by Eli Ruggles of Brookfield, Connecticut, while accompanied by his brother-in-law, Amos Williams, and Nathaniel Noble, an acquaintance who lived nearby in Dexter.

During that winter the Williams and family built a sawmill, which began operations in the spring of 1834.

M-106 has its northeastern terminus at M-36 in Gregory and leads southwest 27 miles (43 km) to Jackson.

[11] Lakelands Trail State Park passes through Unadilla Township.

There were 1,292 housing units at an average density of 38.0 per square mile (14.7/km2).

18.9% of all households were made up of individuals, and 6.1% had someone living alone who was 65 years of age or older.