The renewed agreement will see O2 continue as Ireland's leading rugby sponsors and will include the O2 logo featuring on all of the Ireland senior international and Ireland Wolfhounds teams' playing and training kits, as well as on a wide range of team-related IRFU merchandise.
Announcing the extension of its sponsorship, Stephen Shurrock, Chief Executive of Telefónica Ireland, which operates the O2 brand in the Irish marketplace, said: "I am delighted to confirm O2's continued support of the Ireland team, in what are very exciting times for Irish rugby.
"O2 is extremely proud to have been a loyal partner to the Ireland team over the last five years.
"Declan Kidney, Brian O'Driscoll and all of the players and coaching staff have been incredibly successful, lifting the Grand Slam and numerous Triple Crowns, as well as the spirits of the country.
"We look forward to sharing in the ambitions and successes of Irish rugby in the years ahead, and to bringing our customers and all rugby supporters closer to the action in the process."
Also commenting, John Hussey, President of the IRFU, said: "We are delighted to extend our partnership with O2 as sponsors of the Ireland national team.
"This has been one of the best and most successful sponsorships in Irish sport. We thank O2 for their continued commitment and we look forward to enjoying many more successful years both for O2 and the Ireland team."
As part of today's announcement, O2 and the IRFU have also unveiled plans to hold an open training session with the Ireland squad on Thursday, August 25 at the Aviva Stadium.
The 'O2 Ireland Team Training Session' will allow supporters to get an exclusive view of the squad in their final preparations for the upcoming match against England on August 27, and for the Rugby World Cup in New Zealand.
Admission to the O2 Ireland Team Training Session will be free and entry to the Aviva Stadium is by ticket only. Tickets can be ordered from www.ticketmaster.ie.
Since first becoming official sponsors of the Ireland team in 2006, O2 has created a number of unique initiatives to bring their sponsorship to life, creating a strong bond between the players on the field and the supporters.
In particular, the award-winning 'Be the Difference' campaign has called on supporters to show their passion and support for Irish rugby - from recording their own personalised team talks to be played for the team before key games, to having their names used to form the numbers on the back of each player's jersey.
Over 150,000 rugby supporters have participated in the 'Be the Difference' campaign, which has also been recognised internationally as best-in-class, winning a number of prestigious awards for excellence including a European Sponsorship Association Award and a Cannes Lions International Advertising Award.
O2's support of Irish rugby first commenced in 2002, with the company becoming Official Mobile Telecommunications partners to the IRFU.
O2 is also sponsor of Shannon RFC and has additional partnerships with leading Irish players Brian O'Driscoll, Paul O'Connell and Jonathan Sexton as brand ambassadors.