Alfie will wear the number 9 shirt vacated by Shane Long with the Royals, and spoke to the clubs official website before leaving.
"I want to thank the fans for the unbelievable support they have given me whilst I have been a Rotherham United player,
"It is a great club and I am sure that success is just around the corner. From my perspective ideally both Rotherham and Reading get promoted this season, then maybe we could have a friendly in the new stadium and I can thank the fans properly, that would be ideal.
"I have had some great moments over the past two years and there are one or two highlights that stick out in my mind. The game against Lincoln when I scored twice, they were probably the two best goals that I have scored in my career, and then the game against Cheltenham when I scored four goals, they were special moments."
MillersMAD would like to thank Adam for his service to the club and wish him the very best for the future from all our users.