The Welsh speaking side completed their third win over the Majors this season but were pushed all the way in a tight encounter.
A well worked try from full-back Paul Davies had given his side a 13 point advantage after fly-half Oliver Jenkins slotted two penalties.
Llantwit fought back through tight-head prop David Taylor but couldn’t find the score which would have given them Swalec Bowl glory.
Jenkins fired Clwb Rygbi into the lead after five minutes after Llantwit were penalised for holding on at a ruck.
The outside-half had the chance to extend their lead just two minutes later with another long range attempt, but his strike hit the upright.
But he atoned for his miss with his third kick of the game, stretching his side’s lead to six after the Llantwit Major backs were caught offside.
The side from the Vale of Glamorgan were dealt another blow after 21 minutes when their captain Shaun Shea was forced off due to injury.
And it was to get worse for the Majors as Clwb Rygbi scored their first try of the day through full-back Davies.
Outside-centre Richard Read cut clean through the onrushing defence and delivered a pin-point scoring pass to Davies who crashed over, Jenkins added the conversion.
But Llantwit replied immediately through Taylor. The prop shunted his way over the line from close range before Ryan Evans nailed the conversion from the touchline.
Evans brought his side back into within three points with a penalty, only after Laurence Howley spilled a try-scoring chance – the full-back failed to collect Chris Fowler’s cross-kick and the play was brought back for an earlier offence.
But Jenkins restored Clwb’s six point lead after 66 minutes and they held on to win.
