The Dragons began their Pro12 season with a deserved win over a disjointed Ulster side at Rodney Parade on Friday.
A Roger Wilson try and a penalty from Paddy Jackson saw Ulster lead 8-6 at the end of an error-strewn first half.
Jason Tovey landed a drop goal and a penalty, and followed that up with three penalties in the second period.
A morale-boosting start for the Dragons then while for Ulster, it is the first time in four seasons that they have failed to win their opening game.
Ulster, who won all four of their Pro12 games in Wales during their last campaign, began the game without a number of first-choice players while the Dragons were missing their British and Irish Lions number eight Toby Faletau.
The Welsh side handed debuts to Richie Rees and Rhys Thomas, with second row Andrew Coombs enjoying his first official match as skipper.
The hosts made a bright start and Tovey, back after a year with Cardiff Blues, was off-target with an early penalty opportunity.
The fly-half made amends in the ninth minute however when a beautifully executed left-foot drop goal effort floated between the posts.
Ulster's first incursion into the Dragons half yielded a 13th-minute penalty and Jackson was successful with the resulting kick to level the scores.
Visiting number eight Wilson was then penalised for not releasing the ball quickly enough and Tovey landed the penalty to restore the Dragons' three-point advantage.
Wilson scored the first try of the game in the 17th minute when he carried the ball well and emerged from the back of a driving maul to dive over the line and touch down.
Jackson sliced the conversion wide of the posts and was then unsuccessful with two subsequent very kickable penalties.
Tovey also skewed a penalty wide before the end of an error-strewn first half.
After the interval, Tovey slotted the ball between the posts for his second penalty of the game after Ulster were penalised at the breakdown, and a further three points followed on the hour mark.
The Dragons, who finished 11th in the Pro12 last season, continued to control the game and a 70th-minute penalty from Tovey, his fourth, made it 15-8.
Ulster exerted a sustained period of late pressure as they bore down on the Dragons line, but the home side remained resolute in defence to repeat their victory over the Irish province at the start of the 2009-10 season.
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Dragons boss Lyn Jones told BBC Radio Wales: "It's so easy to reflect just on the result, which was a big positive.
"But the whole performance was very pleasing.
"Ulster are a very, very good side. They are three years into their project and we're just starting ours.
"So we showed a lot of character there. We showed a lot of organisation.
"Our breakdown work was good, our defensive structure was good… and amongst all that the players worked really hard."
Ulster coach Mark Anscombe said: "We were poor - we weren't composed in our decision-making and we panicked a little bit.
"That, combined with an inexperienced referee, combined to frustrate the boys.
"The Dragons played with spirit which we didn't have. I didn't think we were very good at all in an attacking sense."
Dragons: Dan Evans; Tom Prydie, Pat Leach, Jack Dixon, Hallam Amos; Jason Tovey, Richie Rees; Aaron Coundley, T. Rhys Thomas, Dan Way, Matthew Screech, Andrew Coombs (capt), Jevon Groves, Nic Cudd, Lewis Evans.
Replacements: Hugh Gustafson, Phil Price for Way (47), Francisco Chaparro for Coundley (47), Adam Jones for Screech (62), Netani Talei for Groves (63), Jonathan Evans, Kris Burton, Ross Wardle.
Not used: Hugh Gustafson, Jonathan Evans, Kris Burton, Ross Wardle.
Ulster: J Payne; A Trimble, L Marshall, C Farrell, D McIlwaine; P Jackson, P Marshall; C Black, R Herring, R Lutton; J Muller (capt), D Tuohy; R Diack, C Henry, R Wilson.
Replacements: N Annett for Herring (61), T Court, D Fitzpatrick for Black (62), L Stevenson for Tuohy (63), S Doyle for , I Porter for P Marshall (68), J McKinney for Jackson (69), D Cave for Lutton (62).
Referee: Claudio Blessano (FIR)
Assistant Referees: Leighton Hodges, Neil Hennessy (both WRU)
Citing Commissioner: Ray Wilton (WRU)