Sam Vesty started the scoring with a penalty which Barry Everitt equalised late in the half. Soon afterwards, just before half-time, Austin Healey, playing flyhalf, darted and set up a try for wing Alesana Tuilagi.
The Tigers led 8-3 at the break
London Irish crept closer when Everitt goaled his second penalty midway through the second half but then with five minutes to go Tuilagi set up a try for Luke Abraham when he charged down an attempted clearance by Michael Horak. Ross Broadfoot converted.
The Tigers were worried beforehand as they were missing so many top players but they stay secure at the top of the Zurich Premiership. London Irish remain worried as relegation threatens. They had their chances but Rodd Penney lost the ball over the Tigers' line and an Everitt penalty bounced away off the upright.
After the match Gary Gold, the London Irish coach, said: "You don't get many chances to win here so when you get them you have got to take them. Leicester took theirs but we didn't take ours."
For Leicester Tigers:Tries: Alesana Tuilagi, AbrahamCon: BroadfootPen: Vesty
For London Irish:Pens: Everitt 2
Leicester Tigers: 15 Sam Vesty, 14 Dan Hipkiss, 13 Leon Lloyd, 12 Daryl Gibson, 11 Alesana Tuilagi, 10 Austin Healey, 9 Scott Bemand, 8 Will Johnson, 7 Neil Back, 6 Henry Tuilagi, 5 Louis Deacon, 4 Martin Johnson (captain), 3 Darren Morris, 2 James Buckland, 1 Michael Holford.Replacements: 16 George Chuter, 17 John Rawson, 18 James Hamilton, 19 Brett Deacon, 20 Luke Abraham, 21 Ross Broadfoot, 22 Alex Dodge.
London Irish: 15 Michael Horak, 14 Dominic Shabbo, 13 Rodd Penney, 12 Mike Catt, 11 Justin Bishop, 10 Barry Everitt, 9 Paul Hodgson, 8 Roland Reid, 7 Kieron Dawson, 6 Paul Gustard, 5 Nick Kennedy, 4 Ryan Strudwick (c), 3 Rob Hardwick, 2 Adrian Flavin, 1 Neal Hatley Replacements: 16 Doug Wheatley, 17 David Paice, 18 Kieran Roche, 19 Declan Danaher, 20 Nils Mordt, 21 Mark Mapletoft, 22 Kevin Barrett.
Referee: Chris WhiteTouch judges: John Pearson, Don HelmeAssessor: Brian LeighTelevision match official: Nigel Yates