Two first-half tries from Darren Cave, who retired injured at half-time, helped seal the win for Brian McLaughlin's side.
Former Auckland Blues player Jared Payne was handed an Ulster debut and showed some nice touches. He nearly scored at the death, but overall it was a poor game played in occasional driving rain and filled with errors.
As for the Blues, their first League reverse came off the back of a dismal effort as they hardly ever threatened the Ulster line.
The conditions were far from ideal but Ian Humphreys, who also ended up leaving the field injured, will have been disappointed at his early returns from the tee as the Ulster fly-half missed three out of four shots at goal in the opening 20 minutes with his sole success arriving at his second attempt three minutes in.
Still, he did go on to nail his next two efforts, which were conversions after the hosts suddenly sprung into life with two sublime back moves which lifted the game from its torpor.
The first came on the half-hour when Craig Gilroy appeared off his wing over on the left to burst through a space created by Nevin Spence's pass, and as he was felled at the line he popped a scoring pass to Cave.
Three minutes later Humphreys kicked a superb touchline conversion after Cave had scored again. This time it was left winger Ian Whitten who burst through the middle from another Spence feed and Cave slid in at the corner.
With Ulster leading 17-0 at the break, the Blues had an uphill battle in front of them at the start of the second half, although the retirement of Cave with a leg injury offered some encouragement to the visitors.
However, they were unable to profit and some poor handling saw them throw up a couple of good attacking opportunities.
With frustration growing among their ranks, it was little surprise when Xavier Rush was binned in the 54th minute for a high tackle on Pedrie Wannenburg.
The binning nevertheless saw the Blues produce what was easily their most effective period of the game, though all they had to show for it was a Ceri Sweeney penalty three minutes after Rush's return.
A worrying development for Ulster, though, came in the last seven minutes when Humphreys had to be taken off following what looked like a late and high hit by Casey Laulala.
Humphreys' replacement Paddy Jackson kicked an injury-time penalty to stretch the home team's lead to 20-3.
Payne was just held up short of scoring right at the end, but Ulster had already done enough.
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