The 26-year-old, one of three brothers currently playing the game, has enjoyed the best form of his career in 2016 and says he had interest from Australia before opting to make the move to the Black and Whites.
“They are a club that match my ambition,” said the former Wakefield, Huddersfield, Castleford and Batley player, who also had a stint in rugby union with Leeds Carnegie in 2012.
“I want to play in big games in front of big crowds and hopefully push for an international spot, and I believe Hull is the best club to help me do that.
“With the players they have got, it is no fluke that they are top of the table and I’m looking forward to getting stuck in. They tore us to pieces in round one this year and have been massively impressive.
“I had a few clubs who offered me deals and interest in Australia so it was a decision I didn’t take lightly, but as soon as Hull came in for me I had my mind set.”
Hull coach Lee Radford said: “Josh will be a great addition to our squad. He’s a player we have had to put a lot of focus on when coming up against Salford over the last couple of seasons because of his physical presence both in defence and attack and his ability with the ball in hand.
“He has a great skill set and has punished us on a couple of occasions with his goal kicking.
“He’s joining us at a good age and hopefully in the upcoming seasons he can continue to develop as an individual and push for international recognition, as well as helping us to continue in our goal of making this team a real threat in Super League.”