Peel Ports Great Yarmouth and Asco unveiled the 12-year agreement on Tuesday, which will see the energy company take operational responsibility for two more berths at the port.
The two parties say that the arrangement will support the energy sector in Great Yarmouth and the future sustainability of the port.
By working together, they want to support existing customers and attract new ones by offering more flexibility to the oil and gas, renewable energy and decommissioning sectors operating from the port.
The agreement is due to start in January 2019.
Richard Goffin, port director, said: "Through working with Asco, we will be able to harness the enormous potential that Great Yarmouth has as a key base for oil and gas, renewable energy and decommissioning operations.
"We will bring together the best in class expertise and facilities to promote further collaboration, diversify offerings and services offered by both companies and ensure a solid foundation for continued growth and investment at Great Yarmouth.
"Since taking ownership at Great Yarmouth in 2015, Peel Ports has made a series of significant infrastructure investments, which has enabled exponential growth - growth which will undoubtedly be bolstered by this new partnership with Asco."
Glenn Hurren, SNS director for Asco, said: "Our new partnership gives the additional capacity we needed to expand our operations in Great Yarmouth.
"We now have a stronger base for building marine collaboration in the UK Southern North Sea sector and the ability to provide a flexible solution for our customers covering Peterhead, Aberdeen and Great Yarmouth."
Great Yarmouth port has established itself as a centre for the burgeoning renewables industry. It was selected as the construction base for the East Anglia One offshore wind farm, which is due to be completed by 2020, and earlier this month was confirmed as the operations and maintenance base for Vattenfall's two proposed wind farms - which could create hundreds of jobs in the 2020s.