Prop-forward has agreed a three-year deal.
Leeds Rhinos signed Huddersfield Giants forward Anthony Mullally from next season.
The 23-year-old has agreed a three-year-deal.
Leeds Rhinos Head Coach Brian McDermott said, "We are pleased to have secured a player with the potential that Anthony has. We have seen first hand the impact he can have on a game and I am looking forward to working with him from next season."
Mullally added: "It is great to have agreed a three year contract with a club like the Rhinos with all the success they have had over recent years. Huddersfield have been very good to me so I wanted to make sure that I got the process finalised as quickly as possible.
"I have spoken to a number of people who know the Rhinos club and everything I have heard is very positive and I am looking forward to being part of that culture.
"Once 1st May came round and I could speak to other clubs, I was keen to get my future sorted so I can focus on the remainder of my time with Huddersfield until the end of the season.
"I live in Headingley already and I know a few of the boys especially Brett Delaney and I played against Kallum Watkins a lot when we were youngsters so hopefully it will not take long to settle in."