The Millers suffered relegation from the Championship on the final day of the season and there will be a big shake-up at the AESSEAL New York.
At least 10 players will be leaving, with Billy Jones, Shaun MacDonald, Jamie Proctor, Clark Robertson and Kyle Vassell exiting at the end of their contracts.
Jones, who joined in 2018 from Sunderland, spent the second half of last season on loan at Crewe, while Proctor's four-year stay comes to an end, having spent most of that either injured or out on loan.
MacDonald departs after two seasons, having played 37 times for the club.
Robertson was offered a new deal but has turned it down amid links of a return to Aberdeen or a move to another club in the EFL.
Five loan players have also ended their time at the club, with Lewis Wing, George Hirst, Jamal Blackman, Ryan Giles and Florian Jozefzoon all heading back to their parent clubs.
The Millers have offered new deals to out-of-contract duo Matt Olosunde and Josh Vickers.
It goes without saying that it is a sad time of the year when the team splits up, you never get the same dressing room the following year,” Warne said
“The lads who are leaving have all played a part in previous seasons and I would like to place on record my thanks to each and every one of them for their efforts during their time with us.
“We ask a lot of our players here and they are always happy to step up and perform for our great club and our town. On behalf of the players, staff and supporters at Rotherham United I would like to sincerely thank each and every one of them and wish them nothing but success for the future.
“On behalf of everyone at Rotherham United would like to thank each and every player for their contributions to the club during their time at AESSEAL New York Stadium, and we wish them all the best for the future.”