And having been shown around the set up, the 22 year-old said he was delighted to be here despite major interest from other clubs in a higher division.
He told the clubs official website: "I've really enjoyed meeting the staff and the Chairman. Everything has gone well so far and hopefully that can continue onto the pitch. I met the manager and he really sold the club to me. He's very ambitious and that's one of the main reasons why I joined."
Bradley played under Moore's assistant Jimmy Mullen at Walsall and also former Miller Chris Hutchings, and explained about his personal game.
"I was delighted to get my first cap for Wales. It shows I've got a bit of ability and now I want to show that at Rotherham. I like to see myself as a good passer of the ball and a box-to-box midfielder. One thing I need to improve on is my goalscoring but I'm looking forward to showing what I can do.
"I want to play as many games as possible and win as many games as possible. Promotion is the main ambition this season and I think we can achieve it. I'm really happy to be a part of this club," he added.