The 28 year-old played 16 games for the Cumbrians last season and had been first choice for a couple of seasons previously, before falling out of favour at Brunton Park.
And after completing his move to NYS he revealed he expects good things of the Millers.
He said speaking to The Star: “I have played in League One for four years and it is a tough division. It is a physical, competitive league. There are some big teams and quality footballers at that level. A lot of teams play quite direct but you’ve got sides such as MK Dons who are renowned for playing passing football.
“Consistency is the main thing. If we can consistently pick up points, we will be there or thereabouts. This club is very ambitious and we have got a strong squad. If we can make a few more signings then we can do really well."
He adds: “There were a couple of loan options for me back in January and Rotherham showed an interest in me then too. It didn’t come as too much of a surprise that Carlisle weren’t going to offer me a new contract. We struggled last year and on the financial side, the club are not in great shape and I was one of the higher earners.
“Rotherham is a new start. Everything is in place to keep moving forward. The set-up here is amazing.”
Source: The Star