In May 1944, HMS Vanquisher was selected for participation in Operation Neptune, the assault phase of the Allied invasion of Normandy scheduled for early June 1944, and was assigned to Escort Group 106 with the frigate Strule, the corvettes Abelia and Balsam, and motor launches of the Royal Navy Coastal Forces for the operation.

In early June, she joined Escort Group 106 at Milford Haven, Wales, and on 4 June the group, supplemented by two more corvettes and the naval trawlers Caldy and Gweal, rendezvoused with an assault convoy, Convoy EMB 3 – consisting of 11 empty motor transport ships – in the Irish Sea.

On 5 June, the landings were delayed for 24 hours due to bad weather, but on 6 June, the day of the initial landings, Vanquisher and the other ships of her convoy moved to ports on the south coast of England, where the motor transport ships were loaded.

On 7 June, the convoy made its passage to the beachhead, and on 8 June it arrived off the invasion beaches and discharged its cargo.

On 10 June, Vanquisher began escorting convoys carrying reinforcements and supplies from Falmouth to the beachhead, continuing in this role until Operation Neptune concluded toward the end of June.

She then returned to the 6th Escort Group and escorted North Atlantic convoys for the rest of 1944 and into 1945.