The founder of Onninen, Mr. Alfred Onninen, started out as a plumbing contractor in Turku in 1913. In the 1920s the business diversified into heating and plumbing wholesale, gradually extending into different parts of Finland. The company went into ventilation and electrical contracting as well as wholesale of ventilation and electrical products more than 30 years ago.
Internationalization, which began in the 1970s in the form of project exports, has continued for more than a decade through organic growth and through acquisitions. As a result of a reorganization at the end of the 1990s, Onninen gave rise to the Onvest Group.

Today Onninen is part of the Finnish K Group.