He made his debut for Leinster at the age of 19 and the versatile former Blackrock College back featured in Ireland's recent Six Nations campaign.
The talented 25-year-old was selected for the 2009 British & Irish Lions tour to South Africa.
To date he has made 26 international appearances, the last of which unfortunately saw him rupture his anterior cruciate ligament during Ireland's RBS 6 Nations defeat to Italy earlier this month.
Commenting on the news of his contract extension, Fitzgerald said: "I'm delighted to commit my future here. It is hugely frustrating to miss the run-in to the campaign but I'm looking forward to beginning my rehab over the coming weeks and getting back in a blue shirt next season."
Leinster head coach Joe Schmidt added: "We are delighted that a player of Luke's ability has committed his future to the province. At just 25, his best years are ahead of him and hopefully he'll be back better than ever early next season."