Kearney, who is currently receiving treatment for a knee injury, joins a list of international players such as Brian O'Driscoll, Ronan O'Gara and Jamie Heaslip who have agreed new contracts in recent months.
The Louth native has earned 27 Ireland caps to date. He made his Test debut against Argentina in June 2007, and scored his sixth try for Ireland against South Africa last November.
Commenting on the announcement, Kearney said: "I am really happy to have agreed a new contract and it allows me to concentrate on returning to full fitness as soon as possible and putting myself in contention for selection for Leinster and Ireland.
"I have certainly missed playing over the last number of months but my injury is coming along and hopefully I will be back soon.
"There is nothing like representing both Leinster and Ireland and a big deciding factor was our supporters and the fact I think there is a lot more to come in terms of success for both Leinster and Ireland. I am glad that I can be here to remain part of that."
Leinster head coach Joe Schmidt added: "We're delighted that Rob has agreed a new deal with Leinster and Ireland and we look forward to welcoming him back to the fold over the coming weeks.
"Rob has played an important role in the province's recent success and I know how proud he is to represent his home province. Today's announcement is another timely boost for Irish rugby."