Tongan born Hala'ufia joins the West Wales region from London Irish after six seasons with the Aviva Premiership club having made 122 appearances scoring 19 tries. In his first season for the Exiles Hala'ufia played in all Premiership games and helped take his side to the Premiership Final. In the same season he was named Best Newcomer and was crowned Players Player at the end of 2009-10.
The 35 year old powerhouse, who also represented Harlequins in the Premiership, has 20 caps and two tries for Tonga and is the second confirmed number 8 signing for Scarlets with Bridgend born Rory Pitman joining from London Wasps.
Scarlets Head Coach Simon Easterby said: "We're delighted to announce the addition of Chris to the squad for the forthcoming season and beyond. We have consistently stated our intentions to add strength in depth to key areas of the squad. We have always been very clear in our messaging that any new player introduced to the squad has to be right for us and be a good match for our ethos here at the Scarlets.
"The pack has shown time and time again this season that they can compete with the best but we're all very clear that we need to ensure consistency in our performances. Bringing in a player of Chris' ability will see us add not only strength in depth but invaluable experience.
"Chris has a reputation as one of the best number 8s in the game and he brings with him a wealth of experience and all the attributes of a ruthless 8. He's a strong ball carrier and runner but also has the ability to break tackles.
"A player of his experience will help us continue our development as a pack and will be a great support for the younger members of the squad including young number 8 Rory Pitman who joins us from Wasps."
The 6ft 4in destructive Tongan said: "This is a great opportunity for myself to stake a claim in the starting line-up at the Scarlets. I've had six great seasons with London Irish but I'm very much looking forward to a new challenge.
"There are some great players at the region and I'm hoping to play a strong part in the side's PRO12 and European campaigns next season."
See Chris Hala'ufia in action at Parc y Scarlets in 2014-15 with a Scarlets Season Ticket; prices start from as little as £150 for adults and only £8 for juniors.