Full back Hallam Amos scored the only try of the match for the Dragons.
Newport Gwent Dragons Under 18s fended off the challenge from the Scarlets at Rodney Parade to advance to the final of the Regional Competition final.
In a keenly contested encounter, the home side ran out 8-6 victors with full back Hallam Amos scoring the only try of the match mid way through the second half to edge his side in front after the Scarlets had banged over two penalties to nose ahead after Dragons fly half Ethan Davies responded with a first half penalty.
The Dragons will now take on Cardiff Blues in the Regional Competiton final on Wednesday 18 January, at St Helens (KO 7.30pm).
The last five years have been an emotional rollercoaster on and off the pitch for RGC1404. Promotion to the Principality Premiership was the culmination of five years of hard work and investment in North Wales. WRU TV caught up with prop Joe Simpson, who was one of the first intake of WRU North Wales Academy players in 2010.
Ebbw Vale captain Damien Hudd picked up the biggest accolade of the night at the 11th Principality Premiership Awards Evening held at Principality Stadium, after leading his side to the title for the first time.
Wales assistant coach Robin McBryde is predicting a tough battle against England on Sunday despite the fact they may not be considered to be at full strength. Players will be out to impress Eddie Jones which makes England a dangerous proposition, he says.
Wales U20 captain Tom Phillips and performance psychologist Dr Rich Neil explain why spending three days at Monmouth RFC has further strengthened the togetherness of the squad ahead of the #WorldRugbyU20s