Matthew Morgan grabbed two tries as Cardiff hit back from an 11-point half-time deficit to clinch a 43-29 victory over Dragons at the Arms Park.
Adam Warren, Elliot Dee and George Gasson's first-half tries lifted the Dragons into a 21-10 advantage at the interval, but Cardiff came roaring back with a 33-point blitz to pick up a bonus point win as the visitors were run ragged.
Morgan scored two of the Blues' tries with Tom James, Alex Cuthbert and Jarrod Evans also on the score sheet. Evans converted five and added a penalty for a tally of 18 points.
The Dragons suffered two big blows before kick off when wings, Ashton Hewitt and Jarrod Rosser both withdrew with injuries.
However they overcame this setback to take an early lead. Hallam Amos counterattacked and survived a high tackle from Taufa'ao Filise to set up a movement which ended with Gavin Henson sending Warren over.
There was a hint that Henson's pass was forward but the try was awarded and a yellow card issued to Filise for his dangerous tackle.
The Dragons were not ahead for long as the Blues responded with their first try when Kristian Dacey crashed over following a sustained attack.
The frenetic opening continued with a third try when Dee brushed away a weak tackle from Blues' replacement prop, Keiron Assirrati, to score.
Filise returned from the sin-bin in time to see Evans kick a penalty when Dragons infringed at a scrum.
After 32 minutes, the Dragons scored a splendid try when they turned defence into attack. Sarel Pretorius threw a poor pass in his own 22 to put the visitors under pressure but they worked their way out of danger before Tyler Morgan showed exceptional pace to race 70 metres and give Gasson an easy run in.
Just before half-time Evans was short with a penalty attempt so his side still trailed 21-10 at the interval.
For the second half, Matthew Morgan replaced Rhun Williams at full-back and it was he who scored Cardiff's second try soon after the resumption.
However Morgan fumbled the restart for Blues to concede a penalty at the resulting scrum to give Henson a simple three points.
From then on it was one-way traffic and Dragons' resistance finally cracked when a drive from Nick Williams put the visitors on the back foot for James to race outside Pretorius to score.
Moments later the Blues looked set for another but a brilliant cover tackle from Morgan hauled down Josh Navidi after the flanker had raced 50 metres.
It mattered little for Cuthbert crashed over from close range before tries from Morgan and Evans emphasised the Blues' second-half superiority with Lloyd Fairbrother's last minute try earning the Dragons a bonus point.