It was a second victory of the season for the Dragons and, for Ulster, it was a blow to their progress as they finished without even a losing bonus point to take over the Irish Sea.
Ulster could do nothing after the break to prevent a second successive loss, following defeat to the Ospreys last weekend.
The Irishmen began well as they looked to put that defeat behind them and saw fly-half Paddy Jackson put over an early penalty. However after that it was all down hill for the visitors.
The game was effectively over by half-time as a try from Tom Riley and 14 points from the boot of Jason Tovey gave the Dragons a 19-6 lead.
Another Tovey penalty ensured a Dragons victory.
Scorers for Newport-Gwent D’gons: Tries: Riley. Cons: Tovey. Pens: Tovey 5.
NEWPORT-GWENT D’GONS: M. Thomas, Chavhanga, Riley, A. Smith, Poole, Tovey, W. Evans, N. Williams, Willis, Buck, A. Jones, Sidoli, L. Evans, G. Thomas, Coombs.
Replacements: Waters for M. Thomas (65), M. Jones for A. Smith (70), Bedford for W. Evans (61), Buckley for Willis (61), Jenkins for A. Jones (73), Groves for L. Evans (56), O’Driscoll for G. Thomas Ulster scorers: Pens: Jackson 3.
ULSTER: D’Arcy, Gilroy, Spence, L. Marshall, Whitten, Jackson, P. Marshall, Fitzpatrick, Brady, Cronin, Stevenson, Tuohy, Wannenburg, Faloon, Henry.
Replacements: Gaston for D’Arcy (65), Porter for P. Marshall (47), Barker for Stevenson (52), Diack for Faloon (53).
Referee: Neil Patterson (RFU).