Thomas has played in the Heineken Cup with Scarlets
Premiership newcomers Leeds Carnegie have brought in fly-half Ceiron Thomas from Welsh region Llanelli Scarlets
The 25-year-old was the understudy to British and Irish Lion Stephen Jones at Scarlets and he has agreed a two-year deal to become Leeds' sixth signing.
"I am really excited about the challenge of coming to a new club and a new competition," said Thomas.
"I was very impressed with the coaching staff of Andy Key and Neil Back when I spoke to them."
Thomas added: "I knew that Leeds Carnegie was the right club for me when I heard their vision for the team and the club for the coming years.
"I thank the Scarlets for all the encouragement they've given me during my time there.
"I have some great memories from my time with my team-mates and thank the coaches for the opportunities they have given me.
It was a big move for Ceiron to leave his hometown club, and the only team he has ever played for, and we are delighted that he chose Leeds Carnegie as his new home
Leeds director of rugby Andy Key
"I have enjoyed meeting many of the great Scarlets supporters and I'm sure the region will go from strength to strength."
The West Yorkshire side have already captured prop Gareth Hardy, second-row Marco Wentzel, Biarritz winger Henry Fa'afili and back-row Alfie To'oala, while prop Juan Gomez has agreed a permanent deal after spending part of last season on loan from European champions Leinster.
Leeds director of rugby Andy Key explained: "We are really pleased to have signed Ceiron and he will add a lot to our squad.
"It was a big move for Ceiron to leave his hometown club, and the only team he has ever played for, and we are delighted that he chose Leeds Carnegie as his new home.
"He has experience of playing in the Magners League and the Heineken Cup and that will be vital for us in the season.
"We also have Jason Strange as a specialist senior fly half in the squad so the competition between the both will really add to our options."
Thomas played 71 times and scored 288 points for the Scarlets since making his debut in 2003/04 and played 19 times last season.
Scarlets head coach Nigel Davies told the club's website: "We wish Ceiron all the best for the future.
"In a squad featuring the world-class fly-half talent of Stephen Jones he has had to be patient. He has always been an excellent professional."