Teddy Williams followed in the footsteps of his father, the late Owain Williams, in appearing for the Blue and Blacks.
The academy product, who primarily features at lock, has featured for Wales under-20 and made his Cardiff debut against Leinster in 2020.
He also crossed for a match-winning try in the Rainbow Cup derby against Dragons at Cardiff Arms Park, dotting down for the first try of his senior career with the club.