Wätsilä does not disclose the purchase price in its release.
Wärtsilä Entertainment manufactures entertainment equipment and provides lighting, lighting control, audio and public address solutions for cruise ships and amusement parks.
The company became part of the engineering group L-3 Communications in connection with the acquisition of MSI in 2015.
The company for sale has 172 employees in five countries, most of which are in Emden, Germany.
Last year's turnover was about 50 million euros.