The Cowbridge Comprehensive product impressed during the Blues pre-season friendlies, following a stints playing for Cardiff RFC and Plymouth while in university.
He admits linking up with the Blues was a daunting prospect but is determined to establish himself as a regular first team player.
“This is actually my third professional contract,” said Watts-Jones.
“I played down in Plymouth for a few years whilst I was studying at University, but it’s my first professional contract in Wales, which is nice.
“The regional set up is just more professional. As a player all you have to worry about is training hard I suppose, everything else is taken care of.
“The facilities are fantastic, everyone knows what they are doing and the boys work hard.”
“Phil Davies has definitely got our mentalities sorted, there are no big egos, everyone is friendly although there is some great banter in the changing rooms.
“There’s good competition for places and I sit by Josh in the changing room. We wish each other well and whoever starts, whoever gets the jersey, I know will give it one hundred percent.
“It’s a long season, I may start one week he may start the week after. With Phil’s squad rotation you just have to make sure you play well when you have that jersey on your back and that’s about all you can do really.
“I would like to establish myself as a first team squad member and get a few starts in and see how it goes really.”
Watts-Jones went to school with Lloyd Williams and played alongside the Blues and Wales scrum-half as he grew up.
He spent years watching from the terraces at Cardiff Arms Park and admits it would be a dream come true to play at the iconic ground in a competitive match.
“I’ve always wanted to play since I was a little boy going to school at Cowbridge Comprehensive,” said Watts-Jones.
“I lived about five minute’s away form Lloyd and Tom [Williams] so grew up with them.
“I remember mine and Lloyd’s year made it through to the Welsh Cup but lost out to Neath and Port Talbot College in the final. We were unbeatable in the league, so we had a pretty good team really.
“I have a load of friends and people from the Cowbridge area who are season ticket holders and I used to come a lot as a kid. It will be nice to play in front of them.
“I can’t wait to play for the Blues at the Arms Park in a competitive match.”