[5] In February 1997, while being prepared for launch in poor weather, Monmouth's Lynx helicopter slid off the side of the flight deck and sank off the Devon coast.

[6] In October 1997, Monmouth, in company with RFA Orangeleaf and Surcouf, stood by off Pointe Noire in West Africa on Operation Kingfisher in readiness for evacuation in the aftermath of the First Congo War.

Monmouth returned to berth at her home port HMNB Devonport on 3 December 2007 having completed a circumnavigation of the globe, visiting Australia, New Zealand, and Hawaii and taking part in a FPDA exercise.

Monmouth spent June 2011 in the Indian Ocean patrolling the waters off Somalia as part of the ongoing multi-national anti-piracy operations in the region.

[14] In February 2016, Monmouth and her sister HMS Iron Duke participated in NATO exercise Dynamic Guard in Norwegian waters.

[15] In August, Monmouth, in company with HMS Tyne and RFA Argus, anchored off Bournemouth for the town's annual air festival.

[19][20] In June 2017, Monmouth's Wildcat rescued a crewman from the sunken merchant tanker Rama 2 and transferred them to RFA Cardigan Bay for treatment.

[26] On 22 March 2021, it was announced that both Type 23 frigates Monmouth and Montrose would be decommissioned earlier than planned as part of the Ministry of Defence's Integrated Review.