On 15 December 1941 Euryalus, Naiad and eight destroyers deployed from Alexandria under Rear-Admiral Philip Vian as an escort for the freighter MV Breconshire, bound for Malta.

The convoy came under heavy German air attack on 14 February, and the merchant ship Clan Chattan was scuttled.

From 12 to 16 June 1942 Euryalus was part of Operation Vigorous, another Malta supply convoy, starting at Alexandria, Port Said and Haifa.

HMS Euryalus was involved in Operation Avalanche, the amphibious landings at Salerno on 9 September 1943 as part of Rear-Admiral Vian's Task Force 88.

Euryalus joined the 4th Cruiser Squadron at Trincomalee, Ceylon in January 1945, becoming part of the British Eastern Fleet.

On 24 January she took part in Operation Meridian I, covering carrier-launched attacks on refineries at Pladjoe, Sumatra.

On 2 February Euryalus arrived at Fremantle, Australia, to transfer to the British Pacific Fleet (BPF).

On 17 March Euryalus sailed for the US Navy Assembly area at Ulithi to join in USN operations.

On 12 April, as part of Operation Iceberg Oolong, she provided covered during attacks on Shinchiku and Matsugama.

On 27 May Euryalus, with the other ships of the Royal Navy, transferred to US Task Force 37, as changes were made in the organisation of the US Fleet.

On 12 August she took passage to Manus due to a shortage of fuel oil from British support tankers.

On 29 August 1945 she entered Hong Kong with HMS Swiftsure and the landing ship HMCS Prince Robert.

After the end of World War II Euryalus spent 18 further months in the Pacific Fleet operating from Sydney, Japan and Hong Kong before returning to the UK for a year-long modernisation at Rosyth in 1947–48.