Mobile operator Vodafone is to shell out almost €50m over 10 years to sponsor the IRFU - almost double the amount that rival Three Ireland is paying as part of its sponsorship deal.
The arrangement will see Vodafone's logo displayed on the front of the jersey of the Irish rugby national team.
O2 Ireland was previously the sponsor of the IRFU, initially striking a deal in 2006. The two organisations then renewed their partnership in 2011 for another five-year period. However, O2 Ireland's parent company was acquired by Three's parent company, Hutchison Whampoa, in June 2013.
Three took over as official sponsors in the middle of last year and its logo was featured on the Irish jersey for the team's title-winning Six Nations campaign and the autumn Test matches.
It is understood the sponsorship deal with O2 was valued at €2.5m-a-year, before rising to €2.65m when the contract was renewed.
This means Vodafone's new deal, which is believed to be in the region of €50m over a 10- year period, is almost double the value of Three's current agreement.
Three were informed roughly a month ago that the IRFU was looking for a new sponsor before going into talks with Vodafone. Although Three had an option to renew its current deal, they were understood to be unprepared to match the amount on offer from Vodafone.
The new deal will come into effect after next year's Six Nations championship, meaning Three will still be the team's sponsor for the upcoming World Cup campaign.
Both Three Ireland and Vodafone declined to comment when contacted by the Herald. The IRFU had not responded to a request for comment at the time of publication. Three is also the sponsor of the FAI, having announced a sponsorship agreement worth €7.5m over five years at the end of 2010. The contract is up for renewal in mid-2016.
The Vodafone deal is another indication of the increasingly stable financial position of the IRFU, which last year reported a €7.3m surplus for the 2013/14 season.
The surplus was due to improved November series ticket sales and increased prize pots after Joe Schmidt led Ireland to a championship in his debut season.
The deal also marks a significant step forward from the 2012/13 season, when the IRFU revealed a €26m loss in projected earnings from the sale of five and 10-year tickets. The IRFU is expected to unveil more healthy financial figures when it reveals its annual results next month.
The arrangement is the second large sponsorship deal for the IRFU in as many years, after it inked a six-year national teams kit agreement with Canterbury at the start of 2014 that was reported to be worth €20m.
However, this figure did not come close to the €40m Puma agreed with the union when it signed on in 2009, for what was originally intended to be an eight-year deal. Puma opted out earlier in 2013, paying the IRFU an €11.5m sign-off settlement.