Eiffage signed a conditional contract to buy the Smulders Group, which filed for bankruptcy last year, in July.
A statement from the French company stated: "With this acquisition, Eiffage is strengthening its presence on the offshore energy market and in particular the wind one, for which Smulders is a key player.
"This investment also permits the development of the metal branch in its traditional businesses of the offshore energy and complex metal-based constructions abroad, and in northern Europe in particular."
Smulders Projects undertakes project management and engineering for offshore wind and has a plant at Antwerp producing foundations and towers.
The group has supplied monopile and jacket foundations to a number of projects including Horns Rev and Thornton Bank.
Iemants and Willems are Belgian companies supplying high-grade steel constructions, including offshore substations for the London Array, Luchterduinen and Amrumbank West offshore wind farms.
Spomasz, in Poland, manufactures sub-components for towers and foundations.
The businesses are expected to generate about EUR 200 million of revenues in 2013, with 770 employees in Belgium, Netherlands and Poland.
In France Eiffage is competing with international shipbuilding group STX to design and manufacture the foundations and offshore substation for the 500MW St-Brieuc project.
Eiffage has five business divisions – construction, civil works, energy, metal and concessions, which generated revenues of more than EUR 14 billion in 2012, and its metal branch made EUR 900 million last year.