18-year-old Willis impressed last season making appearances for both the Development squad under the watchful eyes of Assistant and Development Coach Brian Dutton and the Under-18s, coached by Head of Youth Miguel Llera.
After catching the eye of first-team manager Darrell Clarke whilst training with his squad, Willis was handed his professional debut in the Leasing.com Trophy, coming on as a substitute against Portsmouth last January.
After rewarding Willis with his first professional contract, manager Clarke is keen to see just how far the teenager can go in the future.
Speaking via the club's official website, Darrell said; "Joe has all the attributes to be a very good player in the future, great energy and technical ability with the right attitude, I’m looking forward to developing him even more next season."