The 15,000 capacity ground will be home to both the Scarlets and their Welsh Premiership side, Llanelli, and is due to be ready for the start of the 2007-2008 season.
The new home for the Scarlets will come hot on the heels of the new stadium being built to house the Neath-Swansea Ospreys in Swansea.
Scarlets Director of Rugby, Gareth Jenkins said: "Stradey park has been a wonderful home for us and we all have fond memories of some huge occasions there. But there is no doubt that if we are going to achieve our ambition of being of one of the top four teams in Europe, we need the best modern facilities.
The proposed 25 acre development will also include an indoor training facility, running track and a 500 seater stand next to an indoor training pitch, and a dormitory for the academy players, securing the future of the Scarlets.
Scarlets chief executive Stuart Gallacher said the partnership with Carmarthenshire County Council, who will own the new stadium offered the regional side an exciting future.
He said, "We simply don't have the money to develop a new stadium ourselves, but this plan will allow us to provide the players and fans with the facilities they deserve. Moving home is always a big upheaval, but this will secure our future.
"We will still be the same club. Standing for the same values and continuing the traditions that are so important to everyone in the area.