Pugh was a dissenting minister, was born at Hendref, Blaenpenal, Cardiganshire, in 1679, and inherited a good estate.
He was trained for the independent ministry at the nonconformist college at Brynllŵarch, near Bridgend, Glamorganshire.
This college, the earliest institution of the kind in Wales, and the parent of the existing presbyterian college at Carmarthen, was founded by Samuel Jones after he was ejected from the living of Llangynwyd in 1662, and on Jones's death in 1697 was transferred to Abergavenny, whither Pugh accompanied it.
He was received as church member at Cilgwyn in 1704, and in October 1709 was ordained co-pastor with David Edwards and Jenkin Jones.
His social position as a landed proprietor in the county was improved by his marriage with an heiress of the neighbourhood, while his power as a preacher and his piety gave him widespread influence.