The £58 million development will be at Dunbeg in County Londonderry and will consist of 14 turbines.
Permission was granted following an appeal against the decision by the Northern Ireland Planning Service. It said the project should be rejected as it would be located in an Area of Outstanding Natural Beauty.
Gaelectric has also finalised the funding for its 4.6MW Skrine wind farm, which will be operational by July. It consists of two 2.3MW Enercon wind turbines.
The company has secured planning permission for 80MW of wind energy developments in Northern Ireland and is progressing 200MW of projects on the island of Ireland.
In March, it received approval for a six turbine 14MW wind farm at Carn Hill near Knockagh, County Antrim.