Hølen was in early times known as a place for production of timber.
The small town of Hølen was, together with the small town of Son, established as a municipality January 1, 1838 (see formannskapsdistrikt). Son and Hølen were separated as municipalities of their own January 1, 1848. Hølen was merged with the rural municipality Vestby July 1, 1943 - and it then lost its status as a town.
Hølen is the smallest municipality (in area) that has ever existed in Norway - the total area was just 0.12 km².