Powell was the son of Walter Rice Howell Powell and his wife Mary Powell. On the death of his father in 1834 he inherited Maesgwynne estate of 3,468 acres (1403 km2) in the parish of Llanboidy, Carmarthenshire, which had been owned by the Howell family. Powell married Mary Anne, daughter of Henry Skrine, of Warleigh Manor, Somerset.
Following her death he married the daughter of Grismond Phillips of Cwmgwilly, and they also had a daughter who married West.F. Roch of Butter Hill, Pembrokeshire.