His career as a preacher started in his home church (Tabernacle, Aberystwyth) in 1848. In 1850 he was admitted to membership of the South Wales Association and was its assistant secretary for two years. He was ordained at Llanelly in 1852, and held temporary or fixed pastorates at the following: Newtown (English), 1850, Alpha church, Builth (1851-3), and again (1856-8), Windsor Street, Liverpool (1853-6), Newtown (1858-9), New Jewin, London (1859-76); then, owing to ill health, he removed to Bangor, though retaining a connection with London until 1882. He m. a Miss Cooper of Llangollen in 1857.

He was closely connected with the educational activities of his church and especially with the training of its ministry. Having refused the principalship of Trevecka in 1863 and 1864, and a tutorship at Bala in 1874, at the end of 1888 he accepted appointment to Trevecka as principal after the death of William Howells (q.v.); a very successful tenure of the post was cut short by his death at Bangor, 26 Sept. 1891.

Davies, despite chronic ill health, was an assiduous lecturer, writer, preacher, author, and teacher, who has many volumes of commentaries, articles, sermons, and lectures to his credit, among the best known being Yr Epistol at yr Effesiaid (two vols.), at y Rhufeiniaid, Epistolau Ioan, Salmau (selection), Darlithiau Athrofaol ar Ysbrydoliaeth y Beibl, Anerchiad ar Fedydd a Swper yr Arglwydd, Ymyl Ei Wisg (sermons), and Darlithiau ar Gristionogaeth, delivered during his memorable London pastorate, 1879-83, and transcribed for Y Traethodydd (1881-4) by Sir E. Vincent Evans (q.v.). He was a powerful thinker whose mind exhibited marked gifts of analysis and synthesis; an inspiring teacher who had long experience of Bible and theological classes; a profound preacher, not by nature eloquent, but for forty years his preaching in the Association meetings of his church made a strong appeal to thoughtful hearers of all ages.