Holt, 27, will stay with the Tangerines until the end of the season after seeing his chances limited at Forest due to the form of fellow strikers Nathan Tyson and Junior Agogo.
Speaking to BBC Radio Lancashire, Blackpool manager Simon Grayson said: "He's a big strong boy and gives us extra competition for places.
"Grant is a player who is hungry to come and play. He's match-fit because he's been playing in their team but is desperate to get an opportunity to prove himself."