"It has been a huge honour to be the first captain of the Blues and I have enjoyed every minute of it. I would like to thank all the players and fans for the support I have received over the last three years. I would also like to wish the best of luck to whoever takes over the captaincy next season - they have my full support."
Dai Young backed Williams's decision: "I fully understand and respect the decision Martyn has made. There's great morale in the squad at the Blues and we are totally united in focusing on what is best for the team.
"I think Martyn's decision reflects this and it is a great credit to him that he wants to put the squad's needs before his own. His decision this season will not rule him out from being the Captain of the Blues sometime in the future and I would like to thank him for his loyal service over the last three years."
The Blues will be announcing the name of their new captain next week. They face Pontypridd in a pre-season friendly on Saturday the 20th of August kick off 2.30pm.