The hosts put their Heineken Cup loss to Northampton behind them to extend their winning run in the competition to 11 successive games. A first-half penalty try was supplemented by second-half tries from Nick Williams and Andrew Trimble in a game which Ulster had to battle hard to triumph and saw them finish with 14 men after Rory Best was yellow-carded late on.
Paddy Jackson kicked a penalty and Ruan Pienaar added nine points for the home side. Ian Madigan made no mistake with his first penalty kick for Leinster before adding a further three and converting Fergus McFadden's late try, but the visitors were unable to score again and make off with a losing bonus point.
Elsewhere the Scarlets consolidated second place in the table with a 9-6 victory over the hapless Cardiff Blues, who have won only once in the league in their first season back at their Cardiff Arms Park home.
It was a tryless, error-strewn affair to set before a season's best 9,872 crowd, the home fans heading for the bars disappointed. There was little imagination in the early exchanges, with aimless kicks the order of the day.
With the Blues scrum soon under pressure, the Scarlets were awarded two penalties in the first 10 minutes and fly-half Aled Thomas slotted over both, and added a third just before the break. His opposite number, teenager Rhys Patchell responded with a penalty in each half for the Blues.
And a first-quarter blitz saw Glasgow claim a 23-14 derby triumph over Edinburgh at Scotstoun to put the Warriors on course for a fourth successive 1872 Cup win.
Scotland's new interim head coach Scott Johnson watched on for the first of a festive double header which effectively acts as a national trial, but it was a Canadian who made the early impression with DTH van der Merwe scoring two tries, either side of a Robert Harley score, as Glasgow raced into a 17-0 lead.
Two Greig Laidlaw penalties and a Piers Francis try reduced the deficit to six points as Edinburgh rallied, but replacement fly-half Duncan Weir kicked two penalties to render a third from Laidlaw irrelevant.
The result saw the Warriors end a four-match losing streak and extend their impressive home run, while it is now nine years since Edinburgh have won in Glasgow and more than two since the capital side won three RaboDirect PRO12 matches in a row.
- Sports & Recreation
- Heineken Cup