After attending the grammar school at Narberth, Pembrokeshire, Waldo studied at the University College of Wales, Aberystwyth, where he graduated in English in 1926.

Willie Jenkins was a pacifist, who had been imprisoned as a conscientious objector in the First World War; he stood as Labour candidate for Pembrokeshire in four elections between 1922 and 1935.

Waldo's famous poem "Cofio" (Remembering) was written in 1931 during a visit to Willie Jenkins's farm at Hoplas, Rhoscrowther, near Pembroke.

[5] Waldo Williams's volume of poetry Dail Pren (Leaves of the Tree) was published in 1956 by Gwasg Gomer.

In the 1959 General Election he stood as a parliamentary candidate for Plaid Cymru in the Pembrokeshire constituency, winning 4.32 per cent (2,253) of the votes.

[7] In the late 1960s, Waldo Williams taught Welsh to children of 10–11 at the Holy Name Catholic School, Fishguard, Pembrokeshire.

He is said to have been a mesmerising teacher, passionate and enthusiastic, who used wooden silhouettes of farm animals with their names painted in Welsh on one side.

He was within the Welsh tradition of the bardd gwlad, poets who served a locality by recording its life and people in verse.

Other well-known poems of his include "Cofio" (Remembering, 1931), "Y tangnefeddwyr" (The peacemakers, 1941), "Preseli" (1946), and "Pa beth yw dyn?"