In a topsy-turvy clash at Stradey Park, Paul Turner's men stormed into a 23-3 half-time lead with a devastating opening period.
The Scarlets were extremely sloppy in the first half and the home support vented their anger at the interval with a chorus of boos. But it had the desired effect on Phil Davies's men who rallied in the second half through tries by Garan Evans and Iestyn Thomas but it wasn't enough to prevent the Dragons from taking home the points.
After a gripping opening to the Magners League season on Friday night between the Blues and the Ospreys the Welsh derby weekend travelled west to finish its journey.
But the ferocious intensity on show at the Arms Park was not witnessed here as a crowd of 5,923 turned up for a match littered with mistakes.
The visitors caught the Scarlets cold with a try after just 59 seconds on the clock. From the kick off, Dragons' Rhys Thomas powered over after wing Richard Mustoe, making his debut on loan from the Ospreys, stunned the Scarlets by taking Aled Thomas's kick. Thomas converted the extras to give Paul Turner's men a dream start.
The Scarlets did not recover as flanker Richard Parks, on his return to the Newport region after a three-year absence following a frustrating season at Perpignan in France, showed his experience and guile as they kept the pressure on in the Scarlets 22. And the Dragons' scrum was firing to allow Thomas to give the Rodney Parade side a 10-point advantage.
Things were to go from bad to worse for Scarlets fly half Cieron Thomas on 13 minutes when Gareth Wyatt intercepted his pass to Matthew Watkins to double the visitors try count. Thomas kicked his second successful kick to put the Dragons three scores in the clear.
The Scarlets pack simply could not cope up front and Thomas nudged his men into a 20-0 lead within as many minutes.
But the West walians rallied and their first attack in the Dragons half was rewarded when Thomas made amends for his error. The Scarlets though fell further behind when Thomas stroked home his third penalty on the half-time whistle.
There must have been harsh words from Scarlets' Director of Rugby Phil Davies at the break because within three minutes of the second half, a long-distance pass from Regan King found Garan Evans in acres of space to lead a potential comeback.
Thomas brought the teams within two scores and the Scarlets stepped on the gas as they smelt victory as Iestyn Thomas burrowed over just five minutes later. Their comeback was made easier after Dragons fly half Thomas was sin-binned for deliberate offside.
But the 14 men gathered themselves with a line-break by Jamie Ringer was well supported by the ever-reliable Parks. The forwards kept hold of the ball before scrum half Andy Williams pounced from two yards. Phil Dollman, kicking instead of Thomas, relieved the pressure.
But the Scarlets refused to gave up and although Cieron Thomas set up a tense finish with a long-range penalty, Paul Turner's men held on to their deserved their win.
Tries: Garan Evans, Iestyn Thomas
Pens: C Thomas (3)
Cons: C Thomas (2)
Tries: R Thomas, Wyatt, A Williams
Pens: A Thomas (3)
Cons: A Thomas (2), Dollman
Scarlets: Stoddart; Garan Evans, King, Gavin Evans, Watkins; Cieron Thomas, Cattle (L Davies 69); John (Iestyn Thomas 40), Hayter (Owens 78), Manu, Eustace, Day (Cooper 40), Jones, N Thomas, Bater (Capt)
Replacements: Edwards, Priestland, J Davies
Dragons: M Thomas (Maule 80); Wyatt, Dollman, Smith, Mustoe; A Thomas, Williams; Black, S Jones (Daly 54), R Thomas (Gustafson 72), L Charteris (capt), A Jones (Sidoli 54), Ringer, Fitisemanu (Lydiate 54), Parks
Replacements: McCarthy, Evans
Yellow Card: A Thomas 56 (deliberate offside)
Referee: James Jones (WRU)