Harmony Township is one of six townships in Union County, Indiana, United States.

As of the 2020 census, its population was 527 and it contained 286 housing units.

[2] According to the 2010 census, the township has a total area of 22.99 square miles (59.5 km2), of which 20.65 square miles (53.5 km2) (or 89.82%) is land and 2.34 square miles (6.1 km2) (or 10.18%) is water.

[4] (This list is based on USGS data and may include former settlements.)

The township contains these two cemeteries: New Hope and Old Bath Springs.