He was educated at Carmarthen grammar school, and on 12 April 1791 matriculated at Wadham College, Oxford.
[2] Taking holy orders, Rees first obtained the curacy of Stoke-Edith and Westhide, Herefordshire; and in 1807 the rectory of Casgob, Radnorshire, where he spent the rest of his life.
The society's edition of the Liber Landavensis was transferred on the death of his nephew Rice Rees to him in 1839, and the book appeared in 1840.
In 1853 Rees also edited for the society Lives of the Cambro-British Saints (text and English translation).
[2] In 1803 Rees published A Short and Practical Account of the Principal Doctrines of Christianity, in 1809 an essay on Clerical Elocution, and in 1811 a tract on pastoral work.