Johnsonville Township was organized in 1879, and named for the fact many of its original settlers had the surname Johnson.

As of the census[1] of 2000, there were 166 people, 58 households, and 49 families residing in the township.

The racial makeup of the township was 98.80% White, 0.60% Asian, and 0.60% from two or more races.

10.3% of all households were made up of individuals, and 1.7% had someone living alone who was 65 years of age or older.

About 6.7% of families and 4.9% of the population were below the poverty line, including none of those under the age of eighteen and 23.8% of those 65 or over.