The 24-year-old defender told BBC Berkshire: "We had a lot of replays and a lot of thrilling games.
"If we can go to the semis this year then I'm sure there'll be a lot of Reading fans who will be happy."
He added: "That's important to us, the magic that we feel and our fans feel."
Brian McDermott's side played the Baggies in last year's competition, winning a fifth-round replay at The Hawthorns to set up a quarter-final with Aston Villa.
Mills continued: "They're playing in the best league in the world - that's where we want to play.
"We have to try and knock them off their perch and that's the attitude that we'll be taking on Saturday."
Reading have lost only one of their last 10 matches, and Mills noted that the confidence around the club is high.
"The performances were so good, even with the draws - we were just lacking that final piece of the jigsaw", he said.
"Winning obviously breeds more confidence. We stuck to our beliefs and it's come good over the Christmas period."
Source: BBC Sport