An Bord Pleanala has given the green light to the North-South electricity Interconnector.
It published its decision, with conditions attached, on its website this morning.
Hundreds of objections had been lodged against the massive project, which also went through a public hearing lasting nearly three months.
An Bord Pleanala cites a number of reasons in today's decision.
It says the interconnector it will remove existing restrictions that limit cross border electricity flows, and provide benefits to the economies of both jurisdictions and for individual consumers.
It also says that having considered the alternatives, a 400 kilovolt overhead line is the most appropriate and cost effective solution for current requirements.
Authorities in Northern Ireland have not yet approved the proposed section of the project planned across the border.