The 31 year old has joined The Reds on loan until January 2 and finds himself reunited with Sean O’Driscoll.
He was Coppinger’s manager at Doncaster for five years and is a keen admirer of the former Newcastle and Exeter man.
Coppiner and The Reds' other new arrival, Billy Sharp, are both in line to make their debuts against Charlton at The City Ground tomorrow (kick-off 3pm).
Chairman Omar Al Hasawi said: "James has great experience of the Championship and I know he is delighted to have the opportunity to work with Sean again.
"He is our 11th signing for Nottingham Forest and I'm sure he will prove to be a great asset for us in the weeks ahead."
Coppinger launched his career as a trainee with Darlington but joined Newcastle as a teenager. He made one league appearances for the Geordies but gained valuable experience of first team football in two loan spells with Hartlepool.
Coppinger joined Exeter in 2002 and over the next two years clocked up more than 80 league appearances.
Doncaster became his next stop in ’04 and he has been a key figure in the South Yorkshire club’s plans since.
He has made more than 300 league and cup appearances for Rovers. He scored a hat-trick in the League One play-off semi-final victory over Southend in 2008 and was in the Doncaster side that beat Leeds in the final.
He had been linked with a move away from Doncaster following their relegation last season and has opted for a second spell under the management of O’Driscoll.
Tickets for tomorrow’s game are available in person from the Forest Ticket Office; on-line at www.nffcretail.com or by calling 0871 226 1980 (calls charged at 10p per minute, mobile rates may vary).