South African back rower Robbie Diack scored the only try as Ulster made it back-to-back wins in the Magners League, edging past a never-say-die Aironi side at Stadio Zaffanella.
Playing their first ever home match in the league, Aironi Rugby faced off against Irish opposition for the second week running. Their coach Franco Bernini kept faith with the team that lost 33-17 away to Munster over the opening weekend.
His Ulster counterpart, Brian McLaughlin, made five changes to the side that secured a 27-26 home win over the Ospreys, with Ireland trio Paddy Wallace, Tom Court and Chris Henry stepping up for their first starts of the campaign.
Nigel Brady and Robbie Diack were also introduced for the Irish province's first ever trip to Stadio Zaffanella, the 34th different venue to stage a Magners League game.
There was no definite pattern to the early exchanges, but French out-half Ludovic Mercier kicked a long range penalty to give Aironi a fifth minute lead.
Ulster were back level by the quarter hour mark and out-half Niall O'Connor's second successful penalty, from a difficult angle on the right, moved McLaughlin's men 6-3 in front.
Ulster enjoyed a purple patch but could not turn possession into points, a forward pass from scrum half Paul Marshall to number 8 Diack spoilt a promising move near the 22.
Aironi were cut to 14 men when their number 8 Nick Williams was sin-binned for coming in at the side and use of abusive language. However, after O'Connor had missed a difficult right-sided penalty, Aironi levelled the tie.
Mercier, who was off target with a drop goal attempt, struck his second penalty from in front of the posts.
Ulster looked lively in attack as the first half came to a close, building through the phases before Henry was presented with a chance five metres out from the hosts' try-line. The Aironi cover got to him, however, and he was knocked into touch.
Still, the men in white took a 9-6 advantage into the break, courtesy of a third penalty from O'Connor.
Aironi were putting it up to Ulster and a drop goal from Mercier, after a wayward Ulster lineout, pulled the Italian side level. As Ulster's error count increased, a Mercier penalty nudged Bernini's charges ahead for the first time at 12-9.
It really was game on as this stage, an intriguing battle ensuing despite the amount of mistakes from both sides. The home crowd willed Aironi on, with Italy head coach Nick Mallett an interested spectator.
Either side of a yellow card for Aironi replacement Gabriel Pizarro for killing the ball, O'Connor had two shots at the posts and he landed the second penalty to get the visitors back on terms.
As the game moved into the final quarter, Ulster made a telling breakthrough. Diack intercepted a loose pass from Mercier and had the pace to make the line to score the game's only try, which O'Connor converted.
Mercier redeemed himself when popping over another penalty to take his personal haul to 15 points, as Aironi took it through the forwards and played to their strengths. Back rowers Gareth Krause and Williams stood out with some strong carries.
Hands in the ruck from number 8 Williams allowed O'Connor stretch Ulster's lead back to seven points.
But the final minutes were far from comfortable for Ulster who lost flanker Pedrie Wannenburg to the sin-bin for not rolling away after the tackle.
Aironi, with their forwards putting in another display full of grit and determination, created one final scoring opportunity from a lineout five metres out.
Williams burrowed his way towards the whitewash, only for replacement scrum half Ian Porter to put his body on the line and position himself so that the Italians were held up over the line.
Winger Giulio Rubini made a half-break in the dying seconds as Aironi tried to get back into the Ulster 22, but try scorer Diack was there to make the all-important tackle.
And as Ulster kept up their defensive guard, a knock on from centre Roberto Quartaroli, in the final play, ended the hosts' brave effort.
The losing bonus point was some consolation for Aironi who face trips to the Scarlets and the Ospreys before the month's end.
The result keeps Ulster at the business end of the table, with McLaughlin admitting afterwards: "We made a lot of errors and our set piece was just not clinical enough, so while the result is pleasing, the performance was less so.
"However, away wins, in particular, are hard to come by and I'm very pleased and a little relieved to have taken the points away from this trip.
"Over the past couple of weeks Aironi have shown that they are more the capable of competing in the Magners League.
"We're not getting ahead of ourselves, it's a very long season but from a results' point of view, it's hard not to be happy with two wins starting off.
"Edinburgh at Ravenhill next Friday will be another tough proposition and we've got plenty to work on," he added.