The Broncos had earmarked Walsh, a potential NRL sensation who played for Australian Schoolboys, for fullback next year. His move to Auckland was described as a "massive blow" by the Brisbane media.
Fullback has become the game-changing position in the NRL, with the likes of James Tedesco (Roosters), Ryan Papenhuyzen (Storm) and Clint Gutherson (Eels) dominant forces at the leading clubs.
Warriors coach Nathan Brown is almost certain to blend Walsh into the first grade lineup at some point this season.
Walsh is a development player at the Broncos, and under NRL rules would not be able to debut in first grade until round 10. He is expected to go into the Warriors first grade squad of 30.
Meanwhile, rumours suggest that young Warriors back Paul Turner, who made his first grade debut last year, could be headed to the Broncos.