During the 20th century, the business has been transformed several times, resulting in the privately owned Ovako of today.

In 1916, SKF purchased Hofors Bruk and became owner of Hellefors Bruk in 1958. An iron mill was founded in Imatra, Finland, in 1935. Steel production escalated and developed at the Imatra steel works through the industrial war reparation effort.

After the second world war, rationalization of the steel business took place world-wide. New steel production technology and automation enabled production of steel of higher quality as well as increased capacity and cost effectiveness.

From the beginning of the 1960’s, the forerunners of Ovako gradually redirected their focus from commercial steel to special steel products. The development required investments in research, product development and quality control.

The works in Smedjebacken, Hofors and Imatra became significant deliverers of steel for the automotive and engineering industries. In 1969, the Finnish companies Oy Vuoksenniska Ab and Oy Fiskars Ab combined their steel production in a new company, Ovako, of which Wärtsilä became co-owner in 1972.

In 1981 Smedjebackens Walsverk and the steel production in Boxholms AB were merged into a new company: Smedjebacken-Boxholm Stål AB. In 1988 that company was bought by Welbond (later Fundia). Smedjebacken-Boxholm Stål became Fundia Steel and later Fundia Special Bar AB. Fundia Steel took over Hallstahammar AB in order to enable further processing of bars. In 1986, the group Ovako Steel was founded through a merger between SKF Steel and Ovako.

In 1991, Fundia was bought by Rautaruukki Oy and the Norweigan Norsk Jern Holding A/S. In 1996 Fundia became a wholly owned subsidary of Rautaruukki Oy. In 1991 SKF became the sole owner of Ovako Steel, while the Imatra operations went on as Imatra Steel.

In May 2005, Ovako was established by merging Fundia, Ovako Steel and Imatra Steel. The company was jointly owned by Rautaruukki, SKF and Wärtsilä, combining their long steel businesses. The next year, Ovako was sold to Pampus Industrie Beteiligungen and a Dutch group of investors:  Hombergh Holdings BV shareholders and WP de Pundert Ventures BV. In 2007, Pampus Stahlbeteiligungs acquired sole ownership of Ovako. Pampus Stahlbeteiligungs was owned by Werner Pampus and his family.

In June 2018, Nippon Steel Corporation, a global market leader in steel production with world-leading technology and production capacity, acquired Ovako.