Wales centre Ceri Sweeney put the Dragons ahead with a sixth-minute penalty, although the hosts had to withstand a fairly torrid opening during which an under-strength Blues side took the upper hand.
However, that changed after 14 minutes when scrum-half Gareth Cooper broke along the left flank, chipped ahead and duly punched the air with delight as Nathan Brew dived on the loose ball for a try Sweeney failed to convert.
Before half-time, however, the Blues were back in contention when number eight and captain Xavier Rush picked up close to the Dragons’ line and muscled his way over for an unconverted try.
Sweeney added a second penalty just before the interval and added a third 16 minutes into the second half to give the Dragons a 14-5 lead.
The Blues hinted at a comeback of sorts when Ben Blair reduced the deficit with a penalty 13 minutes from time but the Dragons looked capable of holding on as the heavens opened and the Rodney Parade pitch caused both sides all sorts of problems.
However, with just eight minutes remaining, replacement flanker Ben White crossed in the corner after a fine handling movement on the right leaving Blair with a chance to edge the Blues in front for the first time.
The former All Black pushed his kick wide of the uprights and with it gave the Dragons a much-needed win.
Tries: N. Brew. Pens: Sweeney 3.
Morgan, Wyatt, Emerick, Smith, N. Brew, Sweeney, Cooper, Black, Daly, Harrison, Hall, Charteris, Charvis, Ringer, Owen.
Hercus for Emerick (35), A. Brew for N. Brew (28), Crawford for Daly (69), Corsi for Harrison (75), Sidoli for Charteris (65), Fitisemanu for Owen (77).
Tries: Rush, White. Pens: Blair. Cardiff Blues: Macleod, Blair, J. Robinson, Shanklin, Czekaj, N. Robinson, Evans, Yapp, G. Williams, Filise, Jones, Goode, Morgan, Shellard, Rush.
Hewitt for Shanklin (69), Fairhurst for Evans (55), Goodfield for G. Williams (73), G. Powell for Filise (61), Davies for Goode (69), White for Shellard (63).
Hugh Watkins (Wales).