FOR acquired the stake for an undisclosed sum from the Danish parent company Global Wind Power Europe.
The move comes after an "extensive process" investigating alternatives for geographical expansion of its onshore wind business, FOR said.
The Oslo-based developer operates nearly 600MW of onshore capacity in the UK and Scandinavia and has a development pipeline of almost 1.5GW.
GWP Europe has developed around 600MW of installed capacity, said CEO Hendrik Amby. It now has a "strong pipeline" at all stages of development, particularly in France, plus Germany and very early-stage development in Morocco.
While FOR undertakes development, construction and operation, GWP France sells its projects to third parties when they are fully consented.
"Our objective is to follow GWP France's existing business strategy, providing financial resources to help grow the business," said FOR CEO David Brunt.