The Peterborough defender spent last season on loan at Chesterfield helping them to promotion to League One, then was loaned out again earlier this season.
He's also had a month long loan stint at Crawley Town inbetween.
The 26 year-old told the Millers official website: "I got a call from Andy Scott, then spoke to my agent and here I am.
"The season's been a bit of a journey for me, I started off training at Peterborough then had a month on loan at Crawley, then came back and then had another month at Chesterfield.
"Travelling up and down can take it's toll so now it's nice to have some stability."
We wish Scott all the best for the rest of the season.