A new cross-border electricity connection will lead to lower consumer costs and ensure a secure long-term supply, an industry body has said.
Infrastructure Minister Nichola Mallon confirmed the North-South interconnector has been given planning permission.
It will create a 400kv overhead electricity line stretching for 138km from Co Tyrone to Co Meath, and has been described as "crucial" for handling growing demand across the island.
But opponents questioned the decision to proceed, claiming it had been rushed and risked an "RHI-style energy debacle".
Applications were previously approved by the Department for Infrastructure in 2018. However, a legal challenge saw the two applications quashed and sent back to officials for determination.
Ms Mallon said the project was "of strategic importance for our island economy".
"The North-South Electricity Interconnector remains crucial to handling growing demand across the electricity transmission systems across the island of Ireland, promoting greater competition within the Single Electricity Market (SEM) for wholesale electricity trading and to protecting security of supply," she said. "It will also enhance network stability and support the future growth of renewable generation and help support our economic recovery from the Covid-19 crisis. These economic and system benefits will benefit citizens across our community."
SONI, the electricity System Operator for Northern Ireland, welcomed the decision, which it said will be a "catalyst" for the region's response to climate change, reduce consumer costs and provide a secure long-term electricity supply.
SONI managing director Jo Aston said the interconnector is "undoubtedly the most important infrastructure scheme on the island today".
Paul Stapleton, managing director of NIE Networks, said: "It will bring increased benefits including improving the reliability and security of supply, enabling cheaper electricity generation and facilitating the connection of more renewable energy to the network."
Jim Lennon, chair of Seat (Safe Electricity Armagh and Tyrone), said: "The world has changed dramatically in the past eight months, let alone the 13 years since the rationale for the interconnector was first put forward.
"Given the painful shortcomings which were exposed by the RHI scandal, it would be rash to proceed with one of the largest investments ever in our energy infrastructure without an up-to-date energy policy framework."