Cian Healy said: "I am delighted to have my new contract signed as it means I can continue to concentrate on playing for my home province and improving my game further.
"It has been a good couple of weeks for us and so I just want to focus on playing well for Leinster to keep me firmly in the plans of Declan (Kidney) and the national team."
Healy has represented Ireland at Schools, Under-19, Under-20, 'A' and full international levels and at only 23 has already won 13 Test caps for Ireland.
The young prop made his Leinster debut in the Magners League in 2007 and has so far appeared for his native province on 68 occasions, winning both the Magners League and Heineken Cup.
IRFU Chief Executive Philip Browne said: "We began the process of contracting players as early as the summer and while it is something that can take time to complete, this is nothing new and we are progressing through the majority of those contracts that are coming to an end this season or early next season.
"It's only in this way that we can continue to have a positive influence on their development and in particular to ensure that our international players are best equipped to contribute to the further success of Irish rugby at international level and also at provincial level."
Ireland head coach Declan Kidney said: "For a young player like Cian who has progressed really well over the last 18 months, this is good news as it allows him to continue to develop as a player in Ireland.
"He has approached every challenge with the same hard working attitude and if he continues to do this he can become an even better player."
Leinster head coach Joe Schmidt added: "Cian is a strong and dynamic ball-carrying loosehead and it was great to see his efforts rewarded with two tries in the recent Heineken Cup win over Clermont Auvergne.
"Cian has been impressive progressing through the Leinster Academy, into the Leinster senior team and onto the Ireland International side.
"At just 23, there is obviously still plenty of scope for further development which promises real benefit for both Leinster and Irish rugby."