Aberdeenshire-based Ecosse Subsea Systems has been engaged to design and lay the cables to connect more than 70 wind turbines off the Humber Estuary to transformer stations.
Ecosse will lay cables with a total length of around 35 miles. It did not name the client that awarded the contract.
The company's owner, Mike Wilson, said: "We've completed countless cable and pipe lay projects in the major oil and gas producing regions but this award is a breakthrough in to the renewables cable-lay market, which could significantly impact on our business."
Mr Wilson said the renewables sector could benefit from the hard lessons technology providers had learned in oil and gas over the past few decades.
Ecosse has spent years working in areas such as the North Sea with oil and gas giants such as Shell and BP. It had £8.4m turnover in the year to March.
The company will recruit an extra 30 people to work on the Humber contract, expected to last up to 10 months. It employs 60 people.
Ecosse previously won a contract from E.ON, the German utility, for seabed preparation work on the Humber Gateway project, off the Yorkshire coast.