The project is being developed in two phases in the Inner Sound of the Pentland Firth, between mainland Scotland and Orkney.
The grid connection of the project has been completed following the installation of the longest underground 33kV power export cables by operator Scottish Hydro Electric Power Distribution (SHEPD) in the UK.
Atlantis CEO Tim Cornelius said: "The connection of our flagship MeyGen project to the SHEPD distribution network marks a huge technical major milestone for Atlantis and the tidal stream industry more broadly.
"It has involved years of hard work, persistence, perseverance and determination by our team and all of the contractors and consultants involved in the onshore work scope. We believe this is now the world’s largest energized grid connection of any commercial tidal stream array.
"We have made great progress over recent months at MeyGen on turbine and foundation preparation and we very much look forward to delivering first power to the grid later this year, which will be a huge event for our company and the global marine power industry."
The connection, which is in line with the National Grid Code, has undergone more than 25km of distribution network upgrades as well as infrastructure upgrades at two substations.
The project is also planned to be connected with high voltage transmission network, which is managed by Scottish Hydro Electric Transmission (SHETL).
Upon commissioning in the second half of this year, the project is expected to generate clean electricity enough to power 175,000 households in Scotland.
The first tidal turbines are expected to be deployed over the coming months.
