Educated at Belfast High School, McCrea has represented Ulster and Irish Schools as well as the Ulster Under-19s.
Delighted with the new deal, he said: "I'm really happy that I have signed a professional contract. This season has been good for me personally but obviously not so good for us as a team.
"I have learnt a lot in the last six months and it is great to be able to turn to Bryn Cunningham, David Humphreys and Paul Steinmetz for advice.
"They are so easy to talk to and have helped me a lot. My only goal at the minute is to get more Ulster caps," he admitted.
Ulster Rugby have also confirmed that former Ireland Under-21 out-half Kieran Hallett has extended his development contract with the province until the end of the current season.