The Ireland international had been linked with a move abroad after a frustrating season, due to injuries and selection issues.
But a deal has been struck for the Heineken Cup winner to remain in Dublin for at least one more year.
We are delighted that Luke has committed to the province for another year. Luke is an outstanding talent and he has played a major role in Leinster's recent success," said Leinster head coach Joe Schmidt.
Fitzgerald, who toured South Africa with the Lions in 2009, is currently on the sidelines again, following neck surgery.
He will miss the beginning of the season and is not expected to be back in action until the New Year.
Leinster have also confirmed the signings of South African second row Quinn Roux and New Zealand born utility back Andrew Goodman.