He worked on the family farm until the age of 18, when he attended a school in Menai Bridge run by Cynffig Davies to prepare candidates for ordination.
He was involved in the preparation of a Welsh-language "short confession of faith" and book of services, serving as secretary of the committee responsible.
Griffith was also part of the committee that worked on a new Welsh translation of the Bible, and was a member of the Council and Court of Governors of University College, Bangor.
He also wrote various theological books: Paul y cenhadwr (1925), Rhai o gymeriadau'r Hen Destament (1927), Y Groes (1943), The Wonderful Life (1941), and Ffynnon Bethlehem (1948).
Griffith died in his son's home in Aberystwyth on 2 February 1967 and was buried in the chapel graveyard in Dwyran, Anglesey.