The UK's Carrier Strike Group will be supported by the American military on its maiden deployment later this year.
Both the UK Defence Secretary Ben Wallace and acting US Secretary of Defense Christopher C Miller co-signed the declaration.
The group, spearheaded by Queen Elizabeth-class aircraft carrier, HMS Queen Elizabeth, has achieved Initial Operating Capability, meaning all elements, from fighter jets to radar and anti-ship weapons, have been successfully brought together and operated.
Mr Wallace said the new agreement between the two countries "paves the way for the US Navy and Marine Corps" to join the Strike Group on on its maiden deployment later this year.
US Marine Corps, Navy personnel and equipment, including a detachment of American F-35B Lightning aircraft and US Navy destroyer USS The Sullivans, will help the group.
The Defence Secretary also said he was "delighted" the UK now has a modern Carrier Strike capability, which has been helped by the "support and cooperation of the United States".
"This deployment embodies the strength of our bilateral ties and reflects the depth and breadth of this vital defence and security partnership," he said.
In December, the Carrier Strike programme achieved initial Operating Capability, following a series of multi-national exercises throughout 2020.
The Carrier Strike Group assembled for the first time last October, while exercising alongside allied nations in the North Sea as part of NATO's Exercise Joint Warrior.
It was revealed earlier this week the Royal Navy spent £39m repairing and maintaining its Queen Elizabeth-class aircraft carriers in 2020.
This included the cost of repairs to HMS Prince of Wales after it suffered flooding.
Cover image: HMS Queen Elizabeth during Exercise Joint Warrior with other vessels as Carrier Strike Group forms (Picture: Royal Navy).