Following consecutive league defeats, Wales’ Capital Region got back to winning ways at BT Sport Cardiff Arms Park thanks to a stunning second-half performance.
The Blues controlled much of a tense first half and took a 9-3 lead into the interval with Steve Shingler exchanging penalties with Tom Homer.
And they burst into the life after the break with Matthew Morgan and Alex Cuthbert crossing in the left corner for quick-fire tries.
A late score by Scott Andrews extended the home's side lead.
The victory sees Danny Wilson’s men remain top of Pool Four and now five points clear of Bath, who they face at the Rec on Thursday.
It took the Blues just three minutes to open the scoring with Shingler knocking over a penalty after Bath pulled down a rolling maul.
They remained in the ascendant in difficult conditions and soaked up Bath’s pressure forcing early turnovers.
A strong charge from Blaine Scully laid the foundations for Shingler’s second penalty with Bath going off their feet at the breakdown.
Tom Homer hit-back for Bath on 13 minutes but the visitors were unable to get going due to incessant unforced errors.
The Blues were in control, with several intelligent kicks pinning Bath back but they were unable to break through.
Shingler booted the scoreboard back into action on 25 minutes but was unfortunate to miss a long-range attempt shortly after the half-hour mark.
Bath almost claimed the opening try as Max Clark sliced through the Cardiff Blues defence in the closing stages of the half.
Fortunately, Matthew Morgan was able to bring the powerful centre down and two phases later the Blues forced a turnover.
They cleared their lines and Clark coughed up the ball up, allowing Cuthbert to hack on as a scramble ensued. Both Willis Halaholo and Josh Navidi went close before the number eight was penalised for holding on.
Bath cleared their lines and the score remained 9-3 to the Blues at the interval.
The visitors made the better start to the half and were quickly camped on the try-line but the Blues held firm and forced another turnover.
After weathering the storm the Blues broke out with Rey Lee-Lo tearing into the Bath half but unable to find Cory Allen in support.
However, the decisive moment soon came as Shingler dummied his way through the Bath defence. He found Cuthbert in support and while the visitors scrambled well, possession was maintained as the wing fed Halaholo.
Lloyd Williams moved the ball left and quick hands from Scott Andrews and Sam Warburton released Morgan in the corner.
With their tails up, the Blues showed no mercy and soon pounced for a second try. Shingler launched a high ball and with a slightly fortuitous bounce Sam Warburton powered through.
He lost his footing in the process of stepping past Homer but the ball was retained and quickly moved wide to Cuthbert.
The wing had worked tirelessly all evening and it was just reward as he displayed devastating pace and power to beat three defenders on his way to the whitewash.
Shingler made no mistake with the conversion from the touchline to open up a commanding 21-3 lead.
The Blues continued to turn the screw and managed to score a third in the final stages of the game, as Scott Andrews powered his way over the line.