 Roberts served in the army in 1940-41 and in the army reserve until 1944.From 1941 until 1944 he worked as Youth Education Officer for Caernarfonshire and in 1944 was appointed lecturer in youth leadership at the University College of Swansea.Goronwy Roberts was elected Labour MP for Caernarvonshire in 1945, when he defeated the sitting Liberal MP Goronwy Owen, who had held the seat since 1923.