Former Australian national league coach Chris Anderson could only sit and watch as the Blues ground out a crucial victory in front of more than 6,000 fans over his Dragons side, who had their share of chances to steal a victory.
The Dragons had the wind at their backs in the first half and kept the ball in the pack with some impressive driving mauls. Ironically, they reaped an instant reward the first time they spun it wide. Centre Hal Luscombe made the break and gave speedy winger Gareth Wyatt the space to dive over in the corner.
The Blues finally entered opposition territory in the 15th minute and burly fly-half Lee Thomas kicked a 40-metre penalty goal.
Incredibly, in only their second sojourn into the Dragons' half, the home side took the lead. Scrum-half Richard Smith dived on a charged-down kick to score his side's first try of the Celtic League season - and his first in 16 months - and Thomas made no mistake with the conversion to give the Blues a five-point lead despite having less than a third of the possession.
Smith went from hero to zero when his mistake allowed Ceri Sweeney to narrow the margin with a penalty goal from in front, but the Blues finished the half on attack and took a 10-8 lead into the changing rooms.
In the second half, it was the Dragons' turn to play into a biting wind and the Blues could smell a much-needed victory. They pressured the visitors into mistakes, Thomas kicked a handy penalty goal, and Dragons boss Anderson sent on Wales international Gareth Cooper in his last throw of the dice.
It nearly worked as the little scrum-half burst through a lineout close to the Blues line, but he was brought down short and the home side held on for a nail-biting victory, with Williams' late try denying the Dragons a losing bonus point.
Cardiff Blues: Tries - R Smith, M Williams; Pens - L Thomas 2; Con - L Thomas.
Newport Gwent Dragons: Try - G Wyatt; Pen - C Sweeney. Halftime: Blues 10-8