Nigel Davies' men had a match-winning 16-point contribution from number 10 Rhys Priestland, while returning centre Jonathan Davies was a force in defence and attack during in this feisty New Year's Day derby
Gareth Maule also touched down for the hosts, while the Dragons had a try apiece from Wayne Evans and Aled Brew, allied to five points from the boot of Jason Tovey.
The men of Gwent, who had lost their last five encounters with the Scarlets, had their festive fixture against the Blues called off.
And their eagerness was obvious in the opening stages as they fought their way to a 10-3 half-time lead. The match had been locked at 3-3 since the 16th minute after fly-halves Priestland and Tovey had exchanged penalties during the first quarter.
Despite the Dragons having the better of territory, the Scarlets missed out on chances to take the lead. Priestland was off target with two penalty goal attempts - one from 40 metres out.
The hosts had a try ruled out by television match official Nigel Whitehouse after full-back Dan Newton had dummied his way through and slid for the try-line. But he held up over the line by a superb covering tackle from Dragons winger Adam Hughes.
The Scarlets' hopes of going in at half-time with a lead increased when Brew was sin-binned for kicking out at Maule after the players had tussled on the ground.
But it was a show and go by Wayne Evans that produced the game's opening try for the Dragons, in the final minute of the first half. The scrum half's break from inside his own half created some space for Tovey out wide and he put a neat kick back infield to send Evans over by the posts.
It took just 64 seconds for the home side to level the scores after the break. The Dragons failed to gather the kick-off and Maule was able to touch down after strong running from his centre partner Davies.
There was more misery for the visitors when they lost influential flanker Gavin Thomas to the sin-bin for persistent infringements at the breakdown.
Priestland kicked the resulting penalty which put the Scarlets ahead for the first time after 46 minutes.
It was a deserved lead, but if the Scarlets thought they were going to continue to put the squeeze on the Dragons they were mistaken. They lost a man of their own when they had centre Davies sin-binned in the 63rd minute, for a ruck offence.
However, the Dragons missed a golden opportunity to draw level. They got no reward from a series of scrums close to the Scarlets' line and Tovey hit a post with a straightforward penalty attempt - much to the delight of the home crowd.
And the Scarlets made the most of the error as Priestland raced over for the Scarlets' second try after good hands from Sean Lamont and replacement Regan King.
As the match entered the closing minutes, Brew cut the deficit to three points with a try after a well-judged crossfield kick by Tovey, but there was still time for a third Priestland penalty to seal the home side's fourth win in five matches in all competition.
The losing bonus point was almost snatched away from the Dragons, but Scarlets replacement Lee Williams could not ground a bobbling ball over the line.
|Scarlets Score Card|
|Newport Gwent Dragons Score Card|