The 22-year-old front rower is the first addition made by Bulls’ new coach James Lowes, and joins from Castleford Tigers.
Dan is a talented young forward, with bags of potential, and we are delighted to have him on board,” said Lowes.
“I believe he can have a good future here at the Bulls, he certainly has all of the necessary attributes to go far,” said Lowes.
Castleford coach Daryl Powell also wished Fleming well, saying: “I would like to wish Dan all the best in his future career, he has been a pleasure to work with and I am confident he will continue to mature into a quality prop in the future.
“His opportunities would have been limited next season and playing in the championship whilst remaining full time is perfect for Dan.”