Brad Arthur and Maika Sivo will reunite with Wiremu Greig at Leeds, where the forward is due to begin a two-year contract in 2027.
Former Cowboys forward Matt Lodge will also be at the Rhinos.
Greig moved to North Queensland from Parramatta before the 2026 season, but has appeared in only three NRL matches for Todd Payten's team this year.
He has played 30 NRL games since making his debut with the Eels in 2021, with regular first-grade opportunities limited throughout his career.
His Cowboys contract expires at the end of this year, and the club has confirmed he will leave Townsville after its final match of 2026.
He is among nine players departing Payten's squad for next season.
The others are Scott Drinkwater, Murray Taulagi, Sam McIntyre, John Bateman, Kai O'Donnell, Jaxson Paulo, Viliami Vailea, Mason Barber and Zac Herdegen.