His try against Munster in the Heineken Cup quarter-final last season was awarded Try of the Season at the 2012 IRUPA Player Awards. He scored two tries for an Ireland XV against the Barbarians in May and three tries for Ireland in last Saturday's non-cap international against Fiji at Thomond Park.
Gilroy was educated at Methodist College before playing club rugby with Dungannon. He has represented Ireland Schools' and was also part of the Ireland Under 20 side that competed in the 2011 Junior World Championships.
Commenting on his contract extension, Gilroy said: "I am delighted that I will be playing my rugby at Ravenhill well into 2016. I am proud to play for my Province - representing Ulster means a great deal to me. Things are going really well at the moment. We have had a good start to both the RaboDirect PRO12 and the Heineken Cup and it is great to be a part of. I am looking forward to helping Ulster be successful over the course of the rest of this season and the next three seasons."
Ulster Rugby Director of Rugby, David Humpreys commented: "I am pleased that a player of the talent of Craig Gilroy has committed to Ulster for the long term. Craig is a product of the Ulster Academy and he fits with our ambition of creating a team of home-grown players capable of competing with the best in Europe. There is no doubt that he is an exceptional rugby player and his future both at Provincial and International level is extremely bright."