Arnold has previously played at Oldham and before that Keighley, where he performed well in 17 games.
Head coach Gary Thornton noted his powerful style of play as key for the Hornets 2023 plans.
He said: “Jack is an experienced front rower and will complement our young squad really well as he’s aggressive, in both attack and defence, and will get us in the front foot with his strong carries.
“He’s a tough and robust middle unit player and a fantastic addition to our group.”
Chairman Andy Mazey also commented about his physical style of play describing Arnold as “a big aggressive unit.”
Arnold expanded: “It’s great to have him with us rather than against us in 2023.
