Lost River Township is one of six townships in Martin County, Indiana, United States. As of the 2020 census, its population was 513 and it contained 250 housing units.
According to the 2010 census, the township has a total area of , of which (or 98.92%) is land and (or 1.08%) is water.
(This list is based on USGS data and may include former settlements.)
The township contains these seven cemeteries: Anderson, Cornel, Emmons Ridge, Green, Jones, Simmons and Walker.