“I am proud of what I have achieved so far in my rugby playing career and remain determined to continue to aspire to win international honours for Wales.
“This has been an extremely difficult decision, but I am absolutely certain it is the correct time for me to enter a new stage of my career.
“My intention is to emerge from the experience of playing for a new team as a better rugby player and to broaden my personal horizons in a new environment.
“I owe a great deal to Wales and to Welsh rugby and I retain today the pride I felt in 2008 when I first pulled on the international jersey for my country of birth.
“As professional players we work immensely hard and there comes a time when you know that a fresh environment will help you retain the sharp edge of determination required to remain a contender for top honours.
“I have enjoyed an incredible time at Cardiff Blues in the company of some great players, coaches, administrators and fans who have helped shape my career.
“I will complete my medical training in March and currently have the opportunity to step outside the academic environment for a couple of years before I take up my required hospital training period.”
Roberts has not yet announced the name of any team he may be joining in the new season.