The subcontract for the vessel, the Sea Fighter, was awarded to the company by BAE Systems.
The vessel is a 262-foot, high-speed aluminum catamaran designed to operate at speeds in excess of 50 knots and is operated by Great Eastern Group for the Office of Naval Research.
Austal Chief Executive Officer Andrew Bellamy said the contract was in line with key company strategies to expand its defense and vessel support businesses.
"This contract is further recognition from the defense community that our core skills add value in the in-service support phase," he said. "It shows we can successfully grow our international support business and leverage our defense contracting credentials beyond new ship construction, in line with our strategy."
Austal provides in-service support to defense vessels in Australia, Oman, Trinidad and Tobago and the United States.
The value of the subcontract is about $1.5 million.
The work is expected to extend into the first quarter of next year.
Austal's U.S. operation this week held a keel-laying ceremony for the second of seven Joint High Speed Vessels it is contracted to design and build for the Navy. It is also preparing to launch its second Independence-variant Littoral Combat Ship for the Navy.