John Laing takes a 30% stake in the 111MW project, which is also owned by German developer Wpd (now 30%) and Gothaer Leben Renewables (40%) – part of the Gothaer Group insurance firm – which acquired a stake in January 2016.
It is the company's first investment in offshore wind, and its second in the German wind market.
In October 2015, John Laing bought the repowered 89MW Klettwitz onshore project in east Germany from developer Ventotec.
"The Nordergründe offshore wind project in Germany is an important step for John Laing into a new market where we see a significant opportunity, and in a country we want to continue to invest into," said John Laing's managing director of renewable energy, Ross McArthur.
Nordergründe is currently under construction 16km off Germany's North Sea coast. It will comprise 18 Senvion 6.15MW turbines.
Foundation installation began in May. All foundations are in place and turbine installation is under way, according to John Laing. It is expected online in Q2 2017.
Wpd closed the financial arrangement for the project in June 2015, with funding from German bank KfW IPEX and the European Investment Bank.
John Laing Group is a minority shareholder of John Laing Environmental Assets, which owns an 82.3MW portfolio of onshore wind projects in the UK.