The estimated value of the new award is £200m.
It has been awarded to Serco directly by the UK MoD, after the culmination of previous 15-year private finance initiative (PFI) arrangements.
The latest contract will come into effect from next month, immediately after the existing PFI ends to ensure continuous delivery of the marine services.
The performance period of this follow-on contract is 27 months, starting from December. It also includes an additional option to extend the contract for another six months.
Serco Group chief executive Rupert Soames said: “Serco is delighted to be continuing to provide these vital services to support RN.
“We look forward to continuing this support for many years to come, drawing on Serco’s increasing global maritime presence to innovate for customers in the UK.”
The company has been providing a wide range of support services to the RN from more than two decades.
The services include trialling new maritime technology, guiding the movement of naval vessels in and out of the harbour, ferrying passengers, providing maintenance support for buoys and moorings, as well as supporting different military training exercises.
Furthermore, the company operates and maintains around 100 tugboats and similar vessels, varying in length from 11m to 93m.
Serco said that all the associated support services are delivered by its team of around 650 engineers and skilled mariners deployed at six different sites across the country and overseas.
The UK-based sites include British Underwater Test & Evaluation Centre in the Kyle of Lochalsh and HMNB Devonport, HMNB Portsmouth and HMNB Clyde.