The forward has been a key member of the Rovers squad who reached the Super 8s Qualifiers this season and will get the chance to train full time for the first time in his career with the Rhinos.
Ormondroyd said: “I’m massively looking forward to joining the Rhinos.
“It will be the first time I have been part of a full time environment and I think that will be really good for me and will help me develop.
“I have spoken with Brian McDermott and Jason Davidson and it will be great to work with them.
“Having the opportunity to work with a full time conditioner is something I am really excited about.
“I currently work full time as community coach with Bradford City so I will have to end that to concentrate on my training.
“I’ve played alongside Jordan Baldwinson, Anthony Mullally and Ashton Golding at Featherstone this year and they’ve all said how much I will enjoy it at Leeds and how good the setup is.
“I was a bit of a latecomer to the game and I started playing when I was 16 as I had previously played football as my dad was a professional footballer and so that was the background I came from.
“Since I have been playing Rugby League my family have all been supportive and my dad loves it and comes to watch all my games.
“I am from East Bierley and supported Bradford Bulls growing up and used to watch their big derby games against Leeds.
“My first club was Drighlington and all the players there looked up to Leeds as they were the local team and were so successful, so it is great that I will be training alongside the Rhinos now.”
The 6ft 5ins front-rower made his Featherstone Rovers debut back in 2013 but established himself this season with 20 appearances for Jon Sharp’s team.
Leeds Rhinos Head Coach Brian McDermott said: “Jack is a player who has impressed us this season and who has potential.
“It will be good to see him in our environment and see how he develops.
“We will be continuing our dual registration arrangement with Featherstone next season and that will allow Jack to continue his develop in games as well.”