The government said SSE Renewables' Stronelairg project would generate power for 114,000 homes and bring Â£30m-worth of benefits to the region.
Landscape charity the John Muir Trust opposes the scheme.
In April, it challenged Highland Council's decision to raise no objection to the wind farm.
The trust lodged a petition in the Court of Session for a judicial review of the local authority's decision.
It warned that the project would "destroy the character" of an area of wild land.
The Mountaineering Council of Scotland also opposed the wind farm.
Following the Scottish government's decision, the council said the project would be a "massively intrusive industrial development" that would be visible from surrounding mountains, including peaks in the Cairngorms National Park.
SSE Renewables had sought permission for up to 83 turbines at Stronelairg near its Glendoe hydro-electric scheme above Fort Augustus.
The scheme was later reduced in size.
SSE said no turbines will be visible from the main tourist routes of the Great Glen, Loch Ness and Cairngorm National Park.
The company's Colin Nicol said the project would bring "real socio-economic benefits" to the Great Glen area including job creation, skills training, business opportunities and community funds.
Mr Ewing said the wind farm would create work during its construction and operation.
He added: "Once it is up and running, the wind farm will save thousands of tonnes of carbon dioxide each year, and will be able to produce enough electricity to power thousands of homes in the Highlands.
"As well as bringing benefits to the local community, the Stronelairg wind farm will also benefit the wider Highland region through the provision of a sustainable development fund."
A 67-turbine wind farm proposed for the Garrogie Estate near Fort Augustus has been given the go-ahead by Energy Minister Fergus Ewing.