The group generated annual sales of about 鈧3.3bn last year.
The acquisition is subject to approval by the Irish antitrust authorities and is expected to be completed over the coming months.
Lynskey, which was established in 1964, is a specialist mechanical engineering services provider, which has operations across Ireland, the UK, and mainland Europe.
It has a wide range of blue chip clients in the commercial, data centre, healthcare, retail and energy sectors. During its latest financial year, it had a reported turnover of about 鈧60m.
The existing employees of Lynskey will be unaffected by the transaction. The senior management team of Lynskey, including its managing director Sean McElligott, will remain in their existing roles after the acquisition goes through.
Mr McElligott said this deal was an 鈥渆xcellent opportunity for both our clients and employees鈥.
鈥淥ur clients will continue to enjoy the same level of superior service provided by our team, delivering complex technical mechanical projects within time and on budget, and post-acquisition will also benefit from the increased scale and service capability we can offer as part of the group,鈥 he said.
Dussmann Technical Solutions division was established in May 2019 and has already made a number of other acquisitions, including the STS Group, which is based in Waterford.
The company said the acquisition of Lynskey adds to the existing portfolio 鈥渋n-house capabilities and brings for the first time the ability to self-perform specialist mechanical services鈥.
Dussmann Group chief executive Wolf-Dieter Adlhoch said the goal with the acquisitions was to 鈥渆stablish and expand our range of engineering services for clients with complex technical demands and mission critical systems in the industrial, energy and data centre sectors.鈥