He becomes Wolves' third signing after Nenad Milijas and Doyle's former Reading team-mate, Marcus Hahnemann.
Unveiled yesterday morning, Doyle thanked Wolves for their expedience.
He said: "The fact that the day the season was over they put in a phone call and had a bid accepted, that interest straight away made me think 'they're keen'.
"They came in and settled things with Reading so they were the first club I spoke to. I was expecting a long summer but Wolves were in straight away.
"I spoke to the manager and chief executive over a week ago and came to the training ground to see everything. I've been making my mind up over the last couple of weeks and am just really pleased the decision has been made.
"The facilities here are top class and it's great to be going back to the Premier League again. I'm sad to be leaving Reading because I had some great years but I'm going with their blessing, which is nice. This is a fresh start."