The 26-year-old, who has won 42 caps for Ireland, has admitted that he is "delighted" to continue in his home nation for a further two years.
"I'm delighted to be continuing my rugby career in Ireland. Leinster Rugby has always been my home and I am very excited to be remaining here to play with a great bunch of players and coaching staff," he told the club's website.
"I have been very lucky to have experienced success with that same group over the last number of year and with the great support we have, it made it a very easy decision for me."
Kearney has made 125 appearances for Leinster.