Ship design capabilities include ferries, tugs, and vessels for the fishing, merchant, offshore and special segments.

Wärtsilä has locations in around 80 countries, including the US, Brazil, Finland, Germany, South Africa, Singapore and China, but operates globally.

[7] Wärtsilä was established when the governor of the county of North Karelia approved the construction of a sawmill in the municipality of Tohmajärvi, Grand Duchy of Finland on 12 April 1834.

In 1938 the diesel engine era began when Wärtsilä signed a licence agreement with Friedrich Krupp Germania Werft AG in Germany.

During the following decades more focus was put on manufacturing diesel and gas engines with the acquisitions of the Swedish firm NOHAB in 1978, the French Société Alsacienne de Constructions Mécaniques (SACM), and the Dutch Stork-Werkspoor in 1989.

The company services the merchant, offshore, cruise and ferry, naval, fishing, tugs, yachts and special vessel markets, and the offering includes ship design, main and auxiliary engines, auxiliary power systems, electrical and automation packages, propulsors (such as water jets, thrusters, propellers, and nozzles), seals, bearings, gears, rudders, scrubbers, boilers, and all related services, such as repair, configuration, upgrading, training, maintenance, and environmental services.

Wärtsilä was an important Finnish shipbuilder from 1935 until 1989, building cruiseferries, cruise ships and a large share of the icebreakers of the world.

In 2016, Wärtsilä signed an agreement to acquire Greensmith Energy Management Systems Inc.[14] In March 2018, the company announced that it had delivered the world's largest[clarification needed] solar hybrid power plant, situated in Burkina Faso.

[16] Wärtsilä's wide energy products and systems footprint includes the US, Germany, the UK, China, Russia, Singapore, Bangladesh, India, Indonesia, Myanmar, Senegal, the Dominican Republic, Australia, Saudi Arabia, Tanzania, Morocco, Argentina, Sierra Leone, Brazil, Finland, Mauritius, Rwanda, Honduras, El Salvador, Kazakhstan, Mexico, Jordan and Oman.

The focus lies on optimising operations and life cycle performance of land based power plants and ship installations.

Key competitors in the energy market include General Electric, Siemens, Mitsubishi Heavy Industries and Ansaldo Energia.

Wärtsilä produces a wide range of four-stroke medium-speed diesel, gas and dual- and multi-fuel engines for marine propulsion, electricity generation on board ships and for land-based power stations.

[31] Common rules and guidance for all employees on Wärtsilä's approach to responsible business practices are defined in the company's code of conduct.