He succeeded his father in 1075 as Prince of Powys. The Chronicle of the Princes of Wales records that "Robert Earl of Shrewsbury" made an alliance with "Cadwgan, Iorwerth and Maredudd, sons of Bleddyn, son of Cynvyn" in 1100 and together they seized "castles…Arundel and Bliv and Brygge…and Shrewsbury". The Chronicle of the Princes of Wales records that "Maredudd son of Bleddyn escaped from prison and returned to his country" in 1104.
The Annales Cambriæ record the death in 1132 of "Maredut filius Bledint dux Powisorum". The Chronicle of the Princes of Wales records that "Maredudd son of Bleddyn" died in 1129. 1