Ormondroyd, who started his career with Rovers, had two years left on his deal with the Championship club.
The 24-year-old made 23 appearances for Featherstone in 2016 to help them reach the Qualifiers, and played a further five times in the Super 8s.
"Jack is a player who has impressed us this season and who has potential," head coach Brian McDermott said.
"We will be continuing our dual registration arrangement with Featherstone next season and that will allow Jack to continue his development in games as well."
Leeds Rhinos have signed prop Jack Ormondroyd from Featherstone Rovers on a three-year contract.