First Minister John Swinney said the £350m facility was strong vote of confidence in Scotland’s people, skills and engineering excellence.
“As the first factory of its kind in the UK, it will help unlock our enormous offshore wind potential while bolstering energy security,” he said.
Swinney attended the opening alongside the UK government’s Scottish Secretary Douglas Alexander.
The Labour MP said: “Scotland is helping to solve one of the biggest challenges in our transition to clean energy, connecting offshore wind to where it’s needed most.”
Sumitomo said the HVDC cables were important in the transport of “massive amounts of Scottish wind power directly to high-demand areas in the rest of the UK”.
The manufacturing plant sits within the Inverness and Cromarty Firth Green Freeport.
This is an area, specially designated by both the Scottish and UK governments, where normal tax and customs rules do not apply in full.