There had been rumours that the Number Eight was set to join French club Toulon.
He follows Sean O'Brien, Paul O'Connell and Keith Earls in signing new contracts with the IRFU in recent weeks.
30 year old Heaslip made his debut for Leinster in 2005 and for Ireland in 2006, claiming 60 caps for Ireland in the process.
Heaslip has welcomed the news, saying “Leinster is where I wanted to continue playing and I am happy that the process is now at end. I am looking forward to playing my role in driving success for both Leinster and Ireland.”
