Cadfan was generally considered to have been a wise and just ruler, noted for his ability to maintain the rule of law and peace during an increasingly hostile period in British history. His memorial stone at Llangadwaladr Church in Anglesey refers to him as "Catamanus rex sapientisimus opinatisimus omnium regum" (King Cadfan the wisest and most renowned of all kings). He was succeeded by his son Cadwallon.
He is one of the last of the legendary kings of Britain as accounted by Geoffrey of Monmouth, who calls him Cadvan and makes him king of the North Welsh, later king of all the Britons.