Reading capture Blackman from Sheffield United
The 23-year old has signed a three-and-a-half-year deal for a fee of around £1.2million after catching the eye of the Royals by scoring 14 goals for the Blades so far this season.
"I'm really looking forward to it and I'm very excited," he told the club's official website.
"I met the gaffer (Brian McDermott) last night, he was fantastic with me and I couldn't have asked any more from him and Nicky Hammond. I can't wait to play - hopefully I can try and get involved as soon as possible."