The former England international had originally decided to call time on his career at the end of last season, but he has now been named on the bench for today's Manchester derby.
"Hearing Scholes is back? What a player.. Couldn't he have waited until after we play United next weekend?," Bolton midfielder Stuart Holden on Twitter.
"The boy is back! The best I've seen!," former United teammate Gary Neville tweeted.
"Henry back at Arsenal and now Scholes back at United. Great to have 2 superstars back in the game," said Everton midfielder Tim Cahill.
Scholes has made 676 appearances for the Red Devils.