The company was established in 1919 as Karjalan Sahko Ltd in Vyborg, Finland. In 1949, the first prototype electric sauna heater was built. During the 1960s the company moved to its current location in Hanko, Finland, and was renamed Helo Tehtaat (Helo Factories). In the 1980s, Helo acquired three of its competitors and production was transferred to a new, purpose-built factory in Hanko.