Flanker Watts-Jones, a product of Cowbridge Comprehensive School, broke into the Cardiff Blues team during the 2012/13 season, making his debut against Connacht in September 2012.
The 26-year-old made 31 appearances for Blues with his last appearance coming against Newcastle Falcons in the LV=Cup when he scored a decisive try.
Watts-Jones has now called time on his professional rugby career following a concussion related injury sustained in November.
After a period of recovery and specialist review, under the guidance of Cardiff Blues medical team, Watts-Jones was advised to retire with his long-term health regarded the highest priority.
Director of Rugby Mark Hammett said: "Rory has been an important and popular member of the squad at Cardiff Blues over the last three seasons. He has always worked tirelessly and put his body on the line for the cause.
"The medical team have worked closely with Rory and his long-term health has always been our utmost priority.
"It's always sad to see a player retire at such a young age, but I know Rory has made the right decision for his future. We will continue to support him during this transitional period.
"I know everyone connected with Cardiff Blues - players, staff and supporters alike - will join me in thanking him for his services to the region and wish him every success for the future."
Statement issued on behalf of Rory Watts-Jones
I am obviously devastated after accepting medical advice that I should retire from rugby. Having put in so much to have my career cut short before I had reached my full potential is hard to take.
Although it will take time to come to terms with my retirement, I take consolation in the fact that I was able to fulfil my childhood dream and represent my home region.
As a professional athlete you always strive to aim higher, and I will always wonder what more I could have achieved in the game. But I have no regrets and I am content that I gave my all in every situation; perhaps ultimately to my detriment.
I would like to take this opportunity to thank the medical team at Cardiff Blues. Their professionalism and support has been outstanding.
I would also like to thank everyone involved in my rugby career, but most importantly my girlfriend and family without whom none of what I achieved would have been possible.
I'd also like to thank all the players I've played with over the years who have made it so much fun and given me so many fond memories. Rugby is a fantastic sport which teaches you so many life values and skills and it has given me so much.
I will forever be a Cardiff Blues fan and I wish the current players and staff all the very best in their careers.
If I could offer one piece of advice it would be to make the most of every minute in the game as you never know when it will be over.
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