She was decommissioned nearly four years ago and is the first ship to be reactivated in this way since the Falklands War.
Although her exterior may look similar to that of dazzle ships, Severn is in fact coloured in the 'Western Approaches' paint scheme – a nod to history and a mark of respect to the sailors who fought and died in the Battle of the Atlantic.
As a development of earlier Royal Navy camouflages, the scheme was first used on World War Two destroyer HMS Broke.
It was then replicated for other destroyers and small ships engaged in anti-submarine operations, designed to "hide" the vessels, according to Severn's Commanding Officer, Commander Phil Harper.
HMS Severn's main role in her second life will combine navigational training, protection of UK waters and fisheries protection.