A product of the club's academy, the 22-year-old striker made only five substitute appearances for his local club in the Premier League.
He said: "I felt I did all I could at Sunderland. I scored a number of goals in the reserves and was working hard in training. I just couldn't get the break.
"There was a point when there were no fit strikers at the club but I was sat there wondering when my time was going to come. I guess my face didn't fit."