Bank of Ireland has committed to being Leinster Rugby's new official sponsor in a €6m deal for the next four years.
Bank of Ireland will receive exclusive branding opportunities with the team's playing and training kit as well as in the new home grounds at the RDS.
Bank of Ireland's Richie Boucher said: "Bank of Ireland has an impressive record of supporting Irish rugby and the opportunity to partner with a team as successful as Leinster is a perfect fit for both our organisations.
"This sponsorship deal is an example of Bank of Ireland's core sponsorship strategy to support Irish sport, not just at national level but also at provincial and community levels."
Leinster chief Executive Michael Dawson responded: "On behalf of everyone associated with Leinster Rugby I am delighted to welcome Bank of Ireland as main sponsors of the Professional Team for the coming seasons.
"Leinster is committed to the pursuit of excellence both on and off the field of play and Bank of Ireland's commitment is testament to the growing stature of the Leinster name, both at home and abroad.
"This contract is the most lucrative in the province's history and we are excited by this new partnership and we look forward to forging strong links with Bank of Ireland and its huge network of customers over the coming years", he concluded.