The new agreement strengthens Bank of Ireland's support for Leinster Rugby as it includes support for grass-roots level right up to the professional senior side.
The new investment in amateur rugby in the province will help to develop the game across all levels from the Under-8 minis to the senior adult competitions. The sponsorship will enhance the support for development officers, coaching materials, equipment and the Coach Development Programme across Leinster.
The sponsorship will also provide support for youth rugby camps and recognise the Club, School, Player and Coach of the Year.
Bank of Ireland will also own the naming rights to youth and adult club competitions and the Bank of Ireland brand will appear on the kits of the Leinster Youth, Leinster School, Leinster Under-19s and Under-20s.
Commenting on the sponsorship extension, Mark Cunningham, Director of Business Banking at Bank of Ireland, said: "We are delighted to extend our sponsorship of Leinster Rugby for another five years. We have been supporting Leinster Rugby since 2007.
"We are particularly delighted to deepen our involvement with Leinster Rugby by providing additional funding for the development of the amateur rugby game in the province.
"Leinster Rugby has a long and proud tradition and at Bank of Ireland we want to help the province to develop players at all levels thus deepening and widening the talent pool which will underpin the sustainability of the game at both amateur and professional levels into the future.
"Sponsoring Leinster Rugby is an excellent fit for Bank of Ireland, as interest and involvement in the game continues to spread rapidly throughout the province this sponsorship provides us with an increased opportunity to engage with business owners, intermediaries and community leaders as we deepen our local involvement and support of Ireland's economic recovery.
"It is a very exciting time ahead for the Bank and Leinster Rugby as we both continue to grow and develop our brands. We are looking forward to seeing all the Leinster Rugby teams build on the successes of last season."
Commenting on the announcement, Leinster Rugby CEO Mick Dawson said: "The key thing for any sports team or organisation is to have stability and the extension of our relationship with Bank of Ireland allows us to build for the future in the knowledge that we have the considerable support of a willing and able sponsor.
"This enhanced deal for both parties allows us to plan behind the scenes and allows us to support Matt O'Connor to the best of our abilities but this new agreement also places a lot of emphasis on the grassroots and while things are beginning to turn, financial support in club land is still difficult to come by.
"The domestic side of the Leinster Rugby family will benefit greatly from this deal and Bank of Ireland are to be thanked for their cooperation in this regard.
"The club is and always will be the lifeline of Leinster Rugby. Without a thriving club scene, there are no players and there is no big game in front of packed RDS."