Aironi, who gained two losing bonus points in their recent defeats to Benetton Treviso, reduced the early deficit to 8-7 with a converted try from flanker Gareth Krause.
Replacement Paolo Buso added two penalties in the second half, putting the pressure on at 15-13. But Ceri Sweeney, who added a penalty and drop goal to his tally, and late replacement Dan Parks kicked the Blues home.
Fly-half Sweeney opened the scoring in the fourth minute, comfortably slotting a penalty after Jamie Roberts had spearheaded a period of ground-gaining play.
David Young's side moved 8-0 ahead when Wales winger Halfpenny, who was making his first start since October owing to an ankle injury, touched down in the eighth minute.
Sweeney knocked a grubber kick forward, the ball evaded the covering Aironi players and the onrushing Tom James, but Halfpenny managed to gather it and canter through for a well-taken five-pointer.
Aironi had a couple of scoring chances in the opening quarter, but their French full-back Julien Laharrague was unsuccessful with penalty attempts in the 6th and 21st minutes.
Cardiff's try-line was breached coming up to the half hour mark, Krause forcing his way over after a well-executed lineout drive from the Aironi forwards. From a tight angle, out-half James Marshall did well to tag on the conversion.
Aironi attacked again, but Sweeney came to Cardiff's rescue when breaking out of their 22 and subsequently winning a penalty.
After warnings to both sides, the visitors had their hooker Fabio Ongaro sin-binned for repeated ruck infringements and Cardiff immediately made use of their numerical advantage.
From a close range lineout, Bradley Davies was driven forward. Aironi could not hold out and hooker Thomas was the man to cross the whitewash. Sweeney's successful conversion was followed by a missed penalty from Marshall, leaving the Italians 15-7 adrift at half-time.
Buso, who came on for Laharrague at half-time, cut the deficit when the Blues managed to concede a penalty against the seven-man scrum.
He added another three points while Cardiff failed to turn their possession into points. The hosts fed a number of kickable penalties into the corner, but Aironi were able to prevent the concession of further tries.
Buso and Halfpenny both missed long range attempts at goal, as the third quarter came to a close. The quality of fare was disappointing, given the calibre of player on show, and kicks eventually won it fo the Blues.
Sweeney eased the tension with an accurate penalty from closer in, and it took some gritty defending from Aironi to keep the Blues out before Sweeney landed his drop goal.
In injury-time, a Parks penalty pushed the winning margin out to a flattering 11 points as the Blues celebrated their second straight league victory.
|Cardiff Blues Score Card|
|Aironi Rugby Score Card|