Hunt has signed a three-year contract at the Madejski Stadium and has arrived for an undisclosed fee.
Hunt's contract at Tannadice was due to expire next summer and United boss Craig Levein feels the SPL club have received a fair price.
Levein said: "This transfer represents an excellent deal for Dundee United and helps bring further financial stability to the club.
"Following an initial enquiry last season, we were aware that Reading might make a formal offer before the close of this transfer window and made plans accordingly.
"We knew that a formal offer would require serious consideration and we knew we had to plan to replace Noel before it became too late to do so."