A former favourite at Stebonheath Park, the 27-year-old made a surprise and high-profile switch to Park Hall in September 2008 and appeared in 20 (+7) Welsh Premier games during his first season at the club, but has gradually fallen out of favour since has only made two substitute appearances this term.
With Richie Partridge cementing the left-sided berth, Williams now gets the chance to resurrect his Welsh Premier career with the Reds.
"I haven’t had much of a chance at TNS this season, so I see this as an opportunity of playing some games and getting some form back," says Williams.
"My contract at TNS is up in May so hopefully I can do well at Llanelli and get a contract offer there for next season.
"The Reds are a great club and I know most of the boys there and I am grateful to Andy Legg for giving me this opportunity. I am looking forward to the challenge"
Under the terms of the loan agreement, Williams will not be able to take part in games between the Reds and his parent club.
Williams played for Carmarthen and had trials for Southampton before playing at Taffs Well and following manager Nick Tucker to Llanelli. He became one of the club's full-time players in 2005 and featured prominently in the successes of 2007/8 before his transfer to TNS.
Photo: Williams scored in the 3-1 League Cup final success over Rhyl last season.