The 18-year-old, who missed most of the 2011 campaign due to injury, made a try scoring debut for Whitehaven in 2010 in the 66-16 defeat at Halifax.
Stuart Barrow, Player Performance Manager at Bradford, coached Rossi in the England Academy and quickly snapped up the teenager when he was alerted to his availability.
Commenting on the deal, Rossi said “I will really develop mentally and physically. It’s a good opportunity to pick up my rugby game.
“Pre-season starts on November 8 and it is going to be hard, but it’s a good challenge and one I need to step up to.”
Gary Hewer, the coach largely responsible for Rossi’s development at Whitehaven said “Jay is a great example at Whitehaven of taking your chance when it comes along after stepping up at the back end of our relegation season.
“We will eventually see him come through at Bradford or another Super League club. The raw material is there to work on.
“He was at Whitehaven for four years and is another example of a local player reaching his potential after taking a local pathway.”
Rossi will join up with fellow West Cumbrian and ex-Wath Brow amateur James Donaldson at Bradford, who is now considered a first-team regular for the Bulls.