Liberty is a town in and the county seat of Union County, Indiana, United States, located about 5 miles (8.0 km) west of the state's border with Ohio. The population was 2,000 at the 2020 census.

The Liberty post office has been in operation since 1824.

The Liberty Courthouse Square Historic District, Liberty Residential Historic District, and Union County Courthouse are listed on the National Register of Historic Places.

According to the 2010 census, Liberty has a total area of 0.86 square miles (2.23 km²), all of it land.

As of the 2020 census, Liberty had a population of 2,000. The median age was 39.2 years. 23.2% of residents were under the age of 18 and 18.0% of residents were 65 years of age or older. For every 100 females there were 96.7 males, and for every 100 females age 18 and over there were 88.8 males age 18 and over.

0.0% of residents lived in urban areas, while 100.0% lived in rural areas.

There were 839 households in Liberty, of which 30.3% had children under the age of 18 living in them. Of all households, 39.7% were married-couple households, 19.2% were households with a male householder and no spouse or partner present, and 32.1% were households with a female householder and no spouse or partner present. About 32.8% of all households were made up of individuals and 14.8% had someone living alone who was 65 years of age or older.

There were 916 housing units, of which 8.4% were vacant. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 7.9%.