Brockaghboy, near Londonderry in Northern Ireland, was only commissioned last month and has a capacity of 47.5Mw.
Tim Ingram, Greencoat UK’s chairman, said it was very pleased with the deal, which follows on from a very busy 2017.
“It is great to start 2018 with the acquisition of a 100% ownership stake in a brand new, good sized, very high load factor wind farm, from very experienced developers.
“The secondary market remains active and there are several wind farms that we now expect to be acquired by others in the near future: as with all our acquisitions, price discipline is paramount."
Laurence Fumagalli of Greencoat Capital added: "Brockaghboy is another great example of UKW's expertise delivering execution certainty and efficiency for both buyer and seller."
The wind farm is accredited to receive 0.9 ROCs (renewable obligation certificates) per MWh from August 2017. The forecast net load factor is 40.5%.
TCI Renewables developed the project alongside ERG.
Greencoat UK used its debt facilities to fund the purchase, with borrowings rising to £415mln in total following the acquisition.
Gearing (debt to gross assets) rises to 27% compared to a maximum gearing limit of 40%.
The FTSE 250- listed group made ten investments last year and they lifted its net generating capacity to almost 700Mw from 420Mw.