Tries from stand-off Rhys Patchell, and centres Gavin Evans and Jamie Roberts, coupled with two conversions and three penalties for a 13-point haul from RBS Six Nations player of the tournament Leigh Halfpenny, were enough to beat the Italian outfit.
Bottom of the table Zebre are still searching for their first win in the league since being formed last summer, but never looked likely to upset the Blues.
It was the Welsh region’s final home match of the campaign, but the conditions meant it was near impossible to give the departing Roberts and Ceri Sweeney a Barbarians-style send-off of running rugby.
Lions and Wales centre star Roberts is joining French big spenders Racing Metro, while former Wales stand-off Sweeney has signed for Exeter Chiefs.
Roberts crashed over for his touchdown late on as the Blues overtook Connacht, who had passed them in the standings on Friday night, courtesy of a win over Edinburgh.
It was only the Blues’ third triumph of the league programme at the Arms Park following their move back from the Cardiff City Stadium.
Zebre were game opponents but lacked the skill, power, pace and confidence to provide a serious challenge. Their only try, from substitute Filippo Cristiano, came in the final minute.