The home side secured a 22-16 win, mainly thanks to the boot of fly half Simon Humberstone. He kicked five penalties and converted Chris Clayton's second half try but Dale McIntosh's side had it far from easy against a plucky Cardiff side.
Indeed, prop Jake Cooper-Woolley had given the Blue and Blacks a superb start, crashing over inside two minutes for the opening score. James Thomas converted and kicked three further penalties but he was outgunned by Humberstone as Pontypridd edged home.
Playing in a new pink strip, Pontypridd were behind within seconds of the kick-off as Cardiff pressed into the home twenty-two to send Cooper-Woolley over for a close range try, converted by outside half Thomas.
On a rare early incursion into their opponents' half, Pontypridd replied with the first of Humberstone's penalties but they were struggling in attack, one Owen Williams break a rare exception.
A second Humberstone penalty further reduced the deficit and when Pontypridd upped their attacking tempo, Clayton breaking through in midfield, Cardiff were penalised and Humberstone put Pontypridd into the lead for the first time.
The contest was being dominated by the referee's whistle, and as Cardiff gained favour in the contact area, Thomas struck back with two penalties in succession, securing an interval advantage of 9-13.
As the second half got underway, a fourth Humberstone penalty narrowed the deficit to a point though Thomas soon responded in kind for Cardiff.
The capital club were giving everything but their momentum was soon stemmed as scrum half Garyn Lucas was sin binned for a high tackle.
Despite boasting a man advantage, Pontypridd were still struggling to hit top gear as they committed a number of errors. It was a performance perhaps befitting of the 12 changes made by McIntosh but they weren't to be denied for long as following a series of forward drives, Clayton crossed, the score converted from a wide angle by Humberstone.
Cardiff responded with a brief phase of pressure but outside half Thomas pulled a penalty wide.
And when Humberstone succeeded where Thomas had failed, it was enough to secure yet another Pontypridd win.
Listen to match reaction by Pontypridd's Cory Hill and Dale McIntosh