Plans to sign the midfielder on a long-term basis until the end of the season had to be revised due to the impact of three other players being quickly transferred from the Premiership club, and the terms of the loan may be changed before the end of the January transfer window, if circumstances allow.
Chesterfield manager Roy McFarland said: "We are pleased to welcome Jamie O’Hara for whatever period we are able to have him and he will be involved in the squad for this weekend’s game at Doncaster."