Anthony Watson and Tom Homer crossed for the visitors and Rob Andrew for the hosts in a bruising encounter played in front of 17,000 supporters.
Leo Halavatau came out of the blocks firing putting a huge hit on former Exile, Richard Thorpe in the first minute. Irish were awarded a penalty after four minutes for an infringement at the lineout by the Tigers. Ian Humphreys stepped up to kick the first points of the afternoon.
Irish crossed for a try on 9 minutes and it was a real opportunistic score. The ball was turned over at the breakdown and fell into the hands of Scott Lawson. The Scottish hooker passed to Shane Geraghty who sent a wide pass to Topsy Ojo who went flying down the right hand flank. Five metres out from the line he passed out of the tackle inside to Anthony Watson to score. Irish led 8-0.
Rob Andrew scored for Leicester on 20 minutes. The Tigers won the ball at the lineout and Andrew powered his way over from a few metres out.
George Ford kicked a penalty on 23 minutes to edge Leicester in front. That was how it remained until a minute before the break when the young Tigers fly half kicked his second penalty. Leicester led 13-8 at the break.
Leicester controlled possession for the majority of the third quarter and were rewarded with two more George Ford penalty goals.
A big moment came with 17 minutes left when Boris Stankovich was shown a straight red card for a high tackle. Irish made the most of their advantage by scoring a try within five minutes. Quick hands by Allinson and Geraghty saw Tom Homer dive in at the corner. Humphries conversion made it a four point game.
The Tigers defended well in the final 10 minutes and limited the Exiles attacking opportunities. George Ford kicked a late penalty goal to confirm the result.
Next up for Irish is Exeter Chiefs at the Madejski Stadium in the Aviva Premiership.
Score sequence (London Irish first): 3-0, 8-0, 8-7, 8-10, 8-13, 8-16, 8-19, 15-19, 15-22
Scorers: London Irish: Penalties: Humphries (4); Tries: Watson (9), Homer (69); Conversion: Humphries; Leicester: Tries: Andrew (21); Conversions: Ford; Penalties: Ford (23, 39, 49, 58, 77)
Leicester Tigers team
5. Mathew Tait; 14. Andy Forsyth; 13. Matt Smith (rep: Andrew Symons, 40; 12. Dan Bowden; 11. Alex Lewington; 10. George Ford; 9. Micky Young (rep: Sam Harrison, 63); 1. Boris Stankovich; 2. Rob Hawkins; 3. Fraser Balmain (rep: Jonny Harris, 67); 4. Rob Andrew; 5. Ed Slater; 6. Michael Noone (rep: Jordan Crane, 63); 7. Richard Thorpe; 8. Brett Deacon (Captain)
Replacements: 16. Jimmy Stevens; 17. Jonny Harris; 18. Kieran Brookes; 19. Joe Cain; 20. Jordan Crane; 21. Sam Harrison; 22. Andrew Symons; 23. George Catchpole
London Irish team
15 Anthony Watson; 14 Topsy Ojo (rep: Tom Homer, 40); 13 Jonathan Joseph; 12 Shane Geraghty; 11 Sailosi Tagicakibau; 10 Ian Humphreys; 9 Darren Allinson; 1 Alex Corbisiero (rep: Max Lahiff, 75); 2 Scott Lawson; 3 Leo Halavatau (rep: Cai Griffiths, 63); 4 George Skivington (rep: Kieran Low, 51); 5 Matt Garvey; 6 Declan Danaher (Captain); 7 Jamie Gibson; 8 Alex Gray
Replacements: 16 Brian Blaney; 17 Max Lahiff; 18 Cai Griffiths; 19. Kieran Low; 20 Chris Hala'ufia; 21 Tom Homer; 22 Steven Shingler; 23 Finlay Barnham
Referee: Ian Davies
Show your "Exile-Style" and wear it with pride!