1834 Wärtsilä is established when the governor of the county of Karelia approves the construction of a sawmill by a rapids in the municipality of Tohmajärvi on 12th April. Some years later the sawmill becomes the property of N. L. Arppe.
1851 The Wärtsilä iron mill is built in place of the sawmill.
1898 The sawmill changes hands and consequently the sawmill and iron works company is renamed Wärtsilä Ab, which becomes a new company called Ab Wärtsilä Oy in 1907.
1908 The power station by Saario rapids starts operating. Wärtsilä has become a modern smelting plant and steel mill running on electricity generated by the rapids it owns.
1926 Wilhelm Wahlforss becomes President of Wärtsilä.
1930 Wärtsilä’s galvanization factory manufacturing magnetically galvanized wire is completed.
1931 Wärtsilä is on the brink of bankruptcy. Workers agree to a 25% cut in wages.
But already in next year Wärtsilä pays a dividend to its shareholders for the first time in a decade.
1935 Wärtsilä acquires a majority holding in Kone- ja Siltarakennus Oy (Machine and Bridge Construction Ltd), gaining also control of the Hietalahti shipyard (est’d 1865) in Helsinki and the Crichton-Vulcan shipyard (est’d 1741) in Turku. Kone- ja Siltarakennus Oy manufactures for example paper machines and Abloy locks. Soon Wärtsilä's headquarters move from Karelia to Helsinki.
1936 Wärtsilä acquires the Onkilahti engineering workshop in Vaasa and the next year the Pietarsaari workshop in the town of Pietarsaari.
1938 Kone ja Silta (Machine and Bridge) group is merged with Wärtsilä, along with the iron mill Taalintehdas (est’d 1686) just acquired, and the Turku, Pietarsaari and Vaasa subsidiaries.
After that Wärtsilä-Yhtymä O/Y (Wärtsilä Group Ltd) is established under chief executive Wilhelm Wahlforss.
1938 The diesel engine era begins when Wärtsilä signs a licence agreement with Friedrich Krupp Germania Werft AG in Germany. The first diesel engine sees the light of day in Turku in November 1942.
1947 Wärtsilä acquires most of the ceramics factory Arabia Ab’s share capital and later the entire company.
1950 Wärtsilä acquires the Nuutajärvi glass factory.
1961 Inauguration of the Wärtsilä Technical College in Joensuu, donated by Wärtsilä.
1961 Bertel Långhjelm is appointed CEO of the group after Wilhelm Wahlforss.
1965 The company is renamed Oy Wärtsilä Ab. The next year the Crichton-Vulcan shipyard is renamed the Turku Shipyard and the Hietalahti shipyard becomes Helsinki Shipyard.
1968 Joensuun Lukkotehdas (The Joensuu Lock Factory) is completed and the manufacturing of Abloy locks is transferred there from Helsinki Factory (former Kone ja Silta Oy).
1970 Tankmar Horn becomes chief executive officer.
1970 Wärtsilä's new Järvenpää factory is completed where e.g. paper machine production moves there from the Helsinki factory.
1971 Sanitary ware production of Arabia is moved to the new factory in Tammisaari.
1974 Wärtsilä begins to build a new shipyard to Perno, Turku, where the whole Turku Shipyard will move by 1983.
1978 Wärtsilä’s head office is moved to Pitkänsillanranta 1 in Helsinki, a property gained by the company when it acquired the John Stenberg engineering workshop in 1975.
1978 Tor Stolpe becomes chief executive officer.
1978 Acquisition of 51% of the NOHAB diesel business from Bofors in Sweden, marking the beginning of Wärtsilä’s international manufacturing operations. The remaining shares are acquired in 1984.
1978 Wärtsilä acquires Björkboda lock factory.
1979 As a result of structural rationalization Taalintehdas is merged with Ovako Oy of which Wärtsilä has the biggest hold.
1979 A new organization is introduced based on six business groups: shipyard, diesel, mechanical engineering, technical porcelain, locks, and consumer goods.
1983 Wärtsilä floats a share series on the Stockholm stock exchange.
1984 Wärtsilä floats its second share issue for international investors and is the first Finnish company to be quoted on the London stock exchange.
1986 A crisis in the global marine industry that had lasted several years leads Wärtsilä to pool its marine resources with Valmet, resulting in the establishment of Wärtsilä Marine Oy. Valmet’s shipbuilding activities are joined with Wärtsilä’s while Wärtsilä’s paper machines are transferred to Valmet.
1986 Wärtsilä Cimtec is formed when Wärtsilä acquires two factory automation companies: GCA Corporation's Industrial Systems division in USA and Oy W. Rosenlew Ab's Automation division in Finland.
1988 A company is set up in India and floated on the Bombay stock exchange. The diesel engine assembly plant in Khopoli is built.
1989 Pekka Laine is named President and CEO in June.
1989 Wärtsilä Marine Oy is filed for bankruptcy in October.
1989 Wärtsilä Diesel acquires the French SACM, a manufacturer of high-speed engines.
Wärtsilä acquires a majority holding in the Dutch company Stork Werkspoor B.V., which makes medium-speed engines. This company is renamed Stork-Wärtsilä Diesel B.V.
1989 Klaus Grönbärj appointed President of Wärtsilä.
1989 Wärtsilä and Lohja sign a merger agreement. Lohja becomes a major shareholder in Wärtsilä after a privileged share issue.
1990 Wärtsilä extraordinary shareholders’ meeting approves the merger plan according to which Wärtsilä will be merged into Lohja, and Wärtsilä shareholders receive as a merger consideration cash and shares of the company formed as a result of the merger.
1990 Wärtsilä sells the majority of Oy Arabia Ab and Rörstrand-Gustavsberg AB to Oy Hackman Ab.