As of 2024, Mounts Bay is the principal vessel assigned to the Royal Navy's Littoral Response Group (North).

[5] Mounts Bay is normally unarmed, but is fitted to receive two 30 mm DS30B cannons, two Mk.44 miniguns, six 7.62mm L7 GPMGs, and a Phalanx CIWS.

[5] As a sealift ship, Mounts Bay is capable of carrying up to 24 Challenger 2 tanks or 150 light trucks in 1,150 linear metres of space.

Mounts Bay demonstrated her lifting capability by transporting in excess of 130 vehicles, for the passage from the UK via Lisbon to Sierra Leone.

After completing the Vela Deployment, she returned to the UK to load vehicles and equipment for Exercise Clockwork in northern Norway.

After discharging her cargo, Mounts Bay returned to the UK, successfully completing operations from the Equator to the Arctic Circle in the last three months of 2006.

Mounts Bay was involved in Exercise Joint Warrior 2008, along with HMS Bulwark, which acted as the Fleets Amphibious Flagship.

She attended The Tall Ships' Races event in Belfast Northern Ireland between 14–17 August 2009 which was the finishing line for the competition.

[12] On Armed Forces Day 2012, 30 June, she fired the salute in Plymouth as she steamed past HMS Argyll, with the Earl of Wessex and the First Sea Lord on board.

[23] After undertaking maintenance in Falmouth in March 2017,[24] Mounts Bay deployed to the Caribbean to provide support during the 2017 hurricane season.

[27][28] In March 2022, Mounts Bay participated in Cold Response 2022, a multinational NATO military exercise in Norway occurring biennially.