Twenty-five-year-old Healy will play for the province to the end of the 2015/16 season; Ross the end of the 2014/15 season.
It has come as a significant boost to Leinster coach Joe Schmidt, who said: "We're delighted that both Cian and Mike have committed their futures to the province. It is a timely boost, not just for Leinster but also for Ireland ahead of the Six Nations."
Schmidt turned first to Healy, a frontrunner for British & Irish Lions honours at the end of the season.
"As a product of the Leinster system with Belvedere College at schools level, then Clontarf at club level before graduating into the Academy system, Cian has proven himself at club and international levels over the last number of seasons.
"He has packed a lot of achievements into his career already with an Under-20 Grand Slam, Magners League and three Heineken Cup titles as well as 35 Ireland caps and 109 Leinster appearances.
"It is hard to believe he is just 25 years of age. We believe that Cian's best years are to come and we are pleased that he will do so in the colours of his home province."
Cornerstone Ross is a pivotal part of the Leinster and Ireland scrum in light of the heretofore unconvincing impact of New Zealand tight-head Michael Bent.
"Mike has been a mainstay of the Leinster squad and a consistent force in both the Leinster and Ireland front-rows over the last few years.
"He has played a key role in our recent successes and his impressive form - in what is one of the most physically rigorous positions in the game - is a testament to his durability.
"Though Cork born, Mike's strong performances over 80 career caps for Leinster have made him very popular with our supporters and they will be delighted that he will also remain in the squad for the coming seasons."