The 32-year-old, who has mae 58 appearances for Wales, made the summer switch from the Scarlets to the Blues and will lead a regional leadership team at the region that has been put in place by Director of Rugby Phil Davies.
Gavin Evans has been appointed vice caption with Andries Pretorius, Sam Warburton, Bradley Davies, Macualey Cook and Rhys Patchell forming the regional leadership team.
“We have picked a core group of players to head up our regional leadership team with Matthew Rees appointed as Captain,” said Davies
“Any of the players can step up and they have been given specific areas to work on.
“Matthew will face stiff competition for his starting place with Rhys Williams, Marc Breeze and Kristian Dacey all performing well for us last year, however, he is a player that understands the standards that I expect of the squad.
“We selected the captain a bit differently last year but this year I know a bit more about the players so it made things easier.
“I have known Matthew for a long time and he is a great leader.
“I canvassed opinion from all around regarding the appointment and it was greeted with enthusiasm.
“He obviously has a lot of experience at regional and international level but what I like about him also is his hunger to do well.
“He’s made the move from the Scarlets to the Blues this summer and still has the hunger for the game and to play international rugby.”
