He was born in 1309, and like his father was a supporter of the de Bohun family. He probably participated in the Scottish Wars under William de Bohun, 1st Earl of Northampton in the 1330s. On 1 February 1338 he set out on pilgrimage on the Camino de Santiago. With the outbreak of the war with France, Devereux was back in support of the Earl of Northampton, and probably participated in the battles of Sluys and of Morlaix, and the campaigns in Brittany. Walter Devereux was in the retinue of the king when Edward III invaded France in 1346. He was present at the Battle of Crécy on 26 August 1346. As a retainer of William de Bohun, he probably fought in the second division. On 10 November 1351, Devereux received a commission with Thomas de Cary, sheriff of Somerset and Dorset, to arrest Nicholas de Poyntz and his servants. Walter Devereux seized Hoke and Stapulford in Dorset on 6 January 1355 following the death of Joan, widow of Robert Syfrewast of Hoke, claiming to be the chief lord of these lands. Devereux held the estates until 1 August 1355 when they were taken into the king's hands. He died without issue about 1359.