[2] Venango Township is located along the northern edge of Butler County.

Located to the north, in Venango County, are Clinton and Scrubgrass townships.

According to the United States Census Bureau, Venango Township has a total area of 21.0 square miles (54.4 km2), all land.

The racial makeup of the township was 99.04% White, 0.14% Native American, 0.14% Pacific Islander, and 0.55% from two or more races.

18.4% of all households were made up of individuals, and 6.9% had someone living alone who was sixty-five years of age or older.