Austin Healey, Ben Kay and George Chuter – all England players of the recent past – and Michael Holford touched down for the Tigers with Andy Goode adding three conversions and three penalties.
The result was harsh on Irish, who created plenty of chances but couldn’t find the telling final pass and only troubled the scorers once with an early Barry Everitt penalty.
And the Exiles were clearly furious with referee Roy Maybank, who disallowed two tries at key moments that shifted the momentum away from the visitors.
They had arrived confident of adding to their only win at Welford Road in 19 attempts against a side short of 10 international players on duty with England, Ireland and Samoa while Julian White was suspended and Graham Rowntree injured.
This season former Australia, Ireland and Leicester fly-half Brian Smith has transformed a perennially struggling side with some judicious signings and consecutive wins over Bath, Newcastle and Gloucester pushed them into the top three.
Leicester, by contrast, had lost two of their last three games but showed an abundance of grit on an icy night to hold on against sustained pressure before punishing defensive errors.
Irish dominated the early stages with confident handling, Everitt got them on the board with a second-minute penalty and Orpington referee Maybank turned down what looked like a perfectly good try when flanker Kieran Roche got over in the right-hand corner. But Leicester simply rolled with the punches and delivered two telling blows when the visitors’ defence was down to lead 18-3 at the interval.
First hooker Danie Coetzee got in Everitt’s way in the eighth minute allowing Healey to charge down the fly-half’s kick and scamper 40 metres for the opening try.
Goode converted and added penalties in the 22nd and 33rd minutes, either side of a Kay try that saw the Lions lock blast round the side of a ruck unchecked and canter 30 metres to the line.
Leicester’s looked out of sight with half-an-hour to go when they added a third try, Chuter emerging with the ball after an old-fashioned drive from a close-range lineout and Goode’s conversion opened up a 22-point lead.
But Irish were denied what might have been a second try when they got over the line again only for Maybank to rule they had infringed moments earlier at a lineout.
Goode kicked the Tigers further ahead and any outside chance of a comeback was killed off when Irish hooker Robbie Russell was sin-binned five minutes after appearing as a late replacement.
Leicester duly celebrated by introducing Seru Rabeni after a year’s absence recovering from a knee injury and again when replacement prop Holford was forced over the line at the death.