The 19-year-old has been at New York Stadium since November and was due to stay until January 17, but has gone back across the Pennines early.
Barker, an England Under-20 international, made his debut in the harrowing 5-2 defeat against Ipswich but was the stand-out performer scoring a fine individual goal.
He was then dropped to the bench for the visit to Leeds and was never able to win back the shirt, playing just 19 minutes in three substitute appearances.
The Millers later also confirmed Barker's exit.We can confirm @BrandonBarker96 has returned from his loan to @OfficialRUFC— Manchester City FC (@MCFC) December 15, 2015
They said in a statement: "Rotherham United can now confirm the paperwork has landed for Brandon Barker’s recall by parent club Manchester City.