Type-23 frigate HMS Kent left Portsmouth Naval Base to take over duties in the Strait of Hormuz from Type 45 defender HMS Duncan.
The move comes after the UK announced it would join the initiative to protect shipping following the seizure of British-flagged vessel Stena Impero by Iranian forces.
A Royal Navy spokesman said: “Type 23 frigate HMS Kent will relieve HMS Duncan of her duties in the Gulf and is scheduled to work alongside US partners as part of the newly-formed international maritime security construct.
“She will be focused on providing regional maritime security, including counter-terrorism and anti-smuggling activities.
“She will also work alongside HMS Montrose to escort British-flagged vessels through the Strait of Hormuz.”
Kent’s commanding officer Commander Andy Brown said: “Today’s departure on operations has been achieved through the hard work and support of the ship’s company, their families and the wider defence enterprise.
“Our focus in the Gulf remains firmly one of de-escalating the current tensions. But we are committed to upholding freedom of navigation and reassuring international shipping, which this deployment on operations aims to do.”
Duncan’s sister ships HMS Defender also deployed from Portsmouth on Monday to head to the Asia Pacific region.
The navy spokesman said: “The deployment aims to strengthen already strong defence ties and demonstrate the UK’s commitment to the peace and prosperity of the region.
“The presence of the ship proves the UK’s global reach with worldwide interests and world-leading defence capability.”