The 22-year-old is a graduate of the Hughes Insurance Ulster Academy and has represented the province at all levels.
He made his senior Ulster debut against Harlequins in August 2010 and rejoined the province last summer from Doncaster Knights where he spent a successful six months playing in the English Championship.
Heaney has played eight times for Mark Anscombe's senior side so far this season.
He was a member of the Ireland Under-20 squad that won the 2010 Six Nations Championship and also competed in the IRB Junior World Championships later that year.
Commenting on his new contract, Heaney said: "I was delighted to have been given the opportunity to come back to Ulster last summer and I am glad that I have done enough this season to have been granted a new contract.
"Ulster has always been home and I am looking forward to representing the province over the next two years."