The 44-year-old spent eight years as a player with the club, winning three Super League titles, two Challenge Cups and a League Leaders Shield.
Lowes has opted to join the Bulls after spending a year as head coach at Leeds Carnegie, whom he led to the Championship playoffs last season.
"We are absolutely delighted to have someone of James's calibre in place as our new head coach," Bulls chairman Marc Green told the club's official website.
"As a board of directors, we recognise his talents, what he has achieved in the game, the names he has worked under and alongside in previous roles, and also what he achieved, last season, with Leeds Carnegie.
"Regardless of what division we play in next year, we believe James is the right man to drive this club forward and into a new era."