Boyd, who began his career at Stevenage, had been the subject of much speculation during the transfer window but was delighted to seal a move to Forest.
He told the club's official website: "This is an exciting opportunity for me at Forest and I want to make the most of it. I didn't know anything about Forest's interest until I got a phone call on Monday evening but when I heard of their interest I was very keen to make it happen.
"At the moment I am here on loan until the end of the season but I sincerely hope it works out for everyone concerned and then we can take it forward from there.
"I would love to think I could help them achieve their immediate ambitions of getting into the Premier League at the end of the season. That would be as special for me as it would for anyone connected with the club."