Motto: I'r Eithaf Dros Yr Eithin.            To The Extreme For The Gorse.

Using the local park field as a ground and the nearby school as changing rooms, this now world famous club was founded in 1922. It immediately began producing players for the first class scene, with the clubs 1st Captain Ifor Mathews making the final Welsh trial playing at scrum half, during his time at Swansea before returning to Cefneithin. In 1924, William John Jones was capped for Wales in the front row against Ireland and later as a headmaster of the local school, he helped form the Mynnydd Mawr Schools Rugby Union.

The club won the Llanelli & District challenge cup 4 times in the 30s & 40s and in 1948, Chairman Hadyn Morris led the club into the West Wales Rugby Union.

Cefneithin will forever be famous within the rugby world, for two former players it provided Welsh rugby. Carwyn James was capped twice for Wales whilst at Llanelli (Australia and France), despite playing at the same time as the legendary Billy Cleaver and Cliff Morgan. Carwyn returned to cap t ain his beloved Cefneithin in 1960. He will however always be remembered for coaching the Legendary 1971 Lions to their awesome victory over the All Blacks some 11years later. He then reproduced that magic by guiding Llanelli and the Barbarians to the same feat. A mentor to many within the game including Graham Henry, his death was a huge blow to the rugby world.

Barry John, who earned his nickname " KING" on the 1971 Lions tour started at Cefneithin in the early 60s. Barry soon went on to write his name in the history books whilst playing for Llanelli, Cardiff, The Barbarians, Wales and The Lions.

Cae Carwyn James was completed in 1976 and Cefneithin now have its first team playing in District 7 West of the national leagues. The clubs Second team has recently won promotion from Section E of the Llanelli & District League.