Lee, 24, has made 188 Super League appearances for Hull, Crusaders, Wakefield and the Giants, and rejected a new deal at the John Smith’s Stadium to make the move south.
Broncos Head Coach Tony Rea said: “Tommy comes to us at an ideal time for both the player and the club. His development as a hooker will be reaching its optimum. His style of play will compliment the way the team plays.
“Tommy represents an ambitious player who looks forward to taking on and conquering the challenges and opportunities in front of him.”