Stretching 80 miles from Herdersbrug on the Belgian coast to Richborough in Kent, the £600 million Nemo Link will help deliver a more flexible energy system for consumers in both countries.
The project is a joint venture between National Grid and Belgian transmission system operator Elia and will enable trade of electricity when it becomes operational in early 2019.
It is capable of providing access to enough energy to power one million homes.
John Pettigrew, Chief Executive of National Grid said: “Nemo Link will bring great benefits to consumers in the UK and Belgium by offering both countries access to a broader energy mix and providing opportunities to expand into other electricity markets.
“This new connection will also provide significant social benefits. By connecting the UK and Belgian electricity markets, we will ensure customers have access to different sources of generation and lower priced electricity. This will mean that customers pay less for their energy.”
The grid operator added it will be investing more than £2 billion in new interconnectors to Europe over the next five years.
Last month, it received financial approval for the construction of the 1.4GW Viking Link, which will connect the UK with Denmark.
Business and Energy Secretary Greg Clark welcomed the launch of the latest project.
He said: “Nemo Link is the UK’s first interconnector since 2012, increasing our electricity capacity from these power cables by a quarter and further enhancing security of supply for us and Belgium.
“Not only will this interconnector help us to accommodate more renewable energy on our grid and provide cheaper, greener energy for consumers as part of our modern Industrial Strategy, it will also see continued and close cooperation on energy across borders with our European partners.”