Tilt has re-joined League One side Wigan Athletic on loan until the end of the campaign while Adam Thompson has mutually agreed to terminate his contract to sign for Leyton Orient.
Defender Tilt made 13 appearances for Wigan during an earlier loan spell this season and has yet to feature for the Millers this term.
Manager Paul Warne feels the move is best for both parties, with the 29-year-old centre-back falling down the pecking order.
"Curtis was obviously on loan there at the start of the season and he came back [when it expired] but he needs to play games because he's come back from a pretty horrendous injury and surgery,” Warne explained.
"He went out to play games and he's come back in. I sat him down and have been completely candid with him. The three centre halves are doing well and at the moment, Robbo is ahead of him in my head in the pecking order which makes him fifth choice centre half.
"If he wants to stay and compete and wait for his opportunity then great, but if after two or three weeks he's going to sit there frustrated that he isn't playing on a Saturday afternoon then he is better off going to play his football elsewhere and I can't blame him for that.
"He wants to play every Saturday and with a squad of 20-odd players it is impossible to do that. Some players see their opportunity to get into the team and believe that that will happen and other players just don't see it.
"Curtis, at this moment in time, feels he is better to go and play somewhere else. He goes with our blessing and we don't hold anyone back here. Hopefully he has a really good end of season and comes back in pre-season when the inaugural battle to get into the team starts again."
Meanwhile, Thompson has joined Orient on a deal until the summer of 2022.
Warne signed the defender from Bury in the summer of 2019 but admitted that game time would continue to be limited for the 28-year-old, who has yet to make an appearance this season.
"He had an amazing season for us last year. I'll always thanks him for that and he will always be close to my heart," added Warne.
"He nearly left in the summer window. I sat down with him and frankly told him my thoughts.
"I didn't think he'd had much game-time this season and it he'd be better furthering his career somewhere else.
"Unfortunately, when a team move up a league sometimes players lose out, we are trying to progress the club.
"He's been brilliant for me, he's never been a moment's problem even though he hasn't played a minute this season. His attitude is spot on and I know he will go on to have a good career.
"He's selected the club he's going to because they have given him an extra year or two years on his contract."
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