Energy regulator Ofgem announced it has approved the link, which will see more than 100 miles of subsea and underground cables laid in the Moray Firth.
At the same time it also announced plans to cut charges for green energy generators.
Ofgem said that from April 1 2016, charges to these suppliers from the National Grid will more closely reflect their use of the network. The watchdog said this would benefit suppliers of wind or solar energy who do not constantly use the grid.
First Minister Alex Salmond welcomed the announcements. He added: "They support the transition to a low-carbon economy by encouraging renewable generation in the areas of highest resource and ensure Scotland continues to play a vital role in delivering security of electricity supply across these islands."
The subsea cable aims to connect 1.2 gigawatts of renewable energy - enough to power the equivalent of almost 640,000 homes - with the grid.
Work on the scheme will be completed in 2018.