The 20-year-old Irish striker was banging the goals in for the reserves last season but boss Kevin Keegan preferred to stick with his senior pros rather than giving Elliott a chance to impress.
He told Sunderland's official website: "City have Nicolas Anelka, Robbie Fowler, Paulo Wanchope and Jonathan Macken and they always seemed to be ahead of me, no matter what I did.
"But you've got to keep your head up and keep going. I've got confidence in my own ability - I'm good at holding the ball up and bringing other people into the game, can score goals and am quite a good finisher," added Elliott, who has signed a three-year deal with the Wearsiders.