"It's a great move for me. The club is definitely heading in the right direction and when you look around the squad you can see the quality on offer," Miller told the club's official website.
QPR boss Paulo Sousa added: "Liam is an international midfielder and will give us great options in that area of the pitch. He's an energetic, box-to-box player who will complement the already positive options we have in the midfield department."