Stuart Gallacher, chief executive of the Scarlets, said: "We wanted to host a showcase match to mark the start of a new chapter in our history at Parc y Scarlets. We are absolutely delighted that the Barbarians have agreed to this fixture.
"It should be a thrilling match. The Barbarians are held in very high esteem and as we know, by their very nature they bring exciting, adventurous rugby to each game. We are hoping for a mix of some of the world's top rugby players from both northern and southern hemispheres in what should be a great game of rugby and a memorable occasion.
"I know Nigel [Davies] and the squad are excited about the prospect - although they are very focused in their current campaign, it's a high-profile additional fixture for the team in the new year which I know they'll relish.
"We believe this will be a fitting way to celebrate our new home and to bring something extra special to our supporters and members this season to thank them for their continued commitment to our rugby region."
Barbarians' president, Micky Steele-Bodger said: "The great figures of Llanelli rugby have had close associations with the Barbarians for many years. R H Williams and Phil Bennett still hold the record for the most Baa-Baas' appearances by Welshmen while Derek Quinnell is a former captain of distinction who now serves on our committee as well as being president of the Llanelli Association.
"I might also add that in 1970 the Scarlets' chief executive Stuart Gallacher was the first member of the Llanelli club to be invited to play for us against a major touring side, the Springboks, at Twickenham.
"We also have fond memories of two earlier fixtures in 1965, to open new accommodation at Stradey Park, and 1972 when we came to Llanelli to play a part in their centenary celebrations. So next January when we come back again we will be honoured to complete a unique treble."
The Barbarians have confirmed today that their 22-man squad for the match will be coached by Welshman, Kingsley Jones. The composition of the squad will be announced in late December. Before that, the club takes part in another historic first, the inaugural rugby union match at the revamped Wembey Stadium. Their side to play in the Olympic Centenary Match against Australia on 3 December includes All Blacks Richie McCaw, Jerry Collins and Joe Rokocoko and Springbok World Cup winning skipper John Smit together with Jean de Villiers, Bakkies Botha and Schalk Burger.
Parc y Scarlets officially becomes the home of the Scarlets in mid- November. The first-ever rugby game at the new stadium will be held on 15 November when Llanelli RFC play Cardiff RFC in the Principality Premiership.
The new stadium's first three games will be at limited capacity as part of the standard licensing arrangements for new stadia. The Scarlets' first game at Parc y Scarlets will be against Munster in the Magners League on 28 November, followed by the first Heineken Cup game against Ulster on 12 December 2008.
Scarlets v Barbarians on 31 January will kick-off at 2.30pm. Details of ticket prices and allocations for this 'one-off' occasion will be released by the region on its website www.scarlets.co.uk following the final game at Stradey Park on Friday 24 October 2008.