A Rey Lee-Lo try was not enough as Ulster battled back to edge to a slender Guinness PRO14 victory at Rodney Parade.
The Samoan centre collected a Jarrod Evans chip to give his side an early lead in Newport but Ulster dominated the majority of the encounter with indiscipline costing the hosts.
Following a sustained period of pressure Mike Lowry danced over to give Ulster the lead and John Cooney kept the scoreboard ticking.
And worryingly, Lee-Lo was stretchered off in the second-half to compound Cardiff Blues woes on a frustrating Monday evening.
The Blues endured a shaky start as they failed to secure the kick-off but they survived the scare and almost scored moments later.
After a hasty clearance, the ball went loose from the ensuing lineout and Lewis Jones hacked through. He appeared to be winning the foot-race but was edged at the final post by Billy Burns, who raced across on the cover.
However, it was Ulster who opened the scoring with a John Cooney penalty, off the left upright, on 15 minutes.
It could have been a lot worse for Cardiff Blues, who weathered a sustained storm in their own 22 with Ulster making good yards through their gargantuan pack but were unable to cross.
While Ulster were unable to cross the whitewash, Cardiff Blues were far more ruthless with ball in hand a lovely strike move off the lineout saw Aled Summerhill float the ball to Matthew Morgan.
It was the kind of opportunity the diminutive full-back finishes and he beat one defender as he cut inside but he was then caught.
The opportunity was lost but the Blues soon claimed the opening try in stunning fashion. A delightful pair of soft hands from Garyn Smith sent Will Boyde tearing through the Ulster defence and while the rampaging number eight was finally hauled down the damage was done.
With the Northern Irish defence at sixes and sevens the ball was spread wide and Evans, knowing Mike Lowry was out of the defence, dinked a ball over the top with perfect precision with Lee-Lo collecting for an easy run in.
Evans added the extras but that was to be the last time Cardiff ventured into the Ulster half as the visitors dominated the second quarter.
They hammered at the Blues line time and time again, turning down multiple shots at goal as they benefitted from the refereeing of Sam Grove-White, who binned Olly Robinson on 37 minutes.
On a number of occasions, it appeared as though the rock solid home scrum had secured possession only for the Scottish official to give Ulster a reset and with the penalty count now at 12-1 to the visitors they got their break through as electric Lowry skipped through the Blues desperate defence.
The try gave the visitors an 8-7 lead but Burns was unable to add the extras as they took the one point advantage into the interval.
Ulster continued where they left off in the second-half but the game was brought to a lengthy halt following a heavy collision involving Lee-Lo.
The star centre was left on the turf and received ten minutes of treatment before being stretchered off, with Garyn Smith, who had just come off, called back into action.
Thankfully the Samoan ace gave a thumbs up as he left the field and the game continued with Ulster in the ascent.
Ten minutes later Cooney added a long-range penalty to stretch his side’s advantage to four as the game entered the final quarter.