The store group is prepared to take its case to the European Court of Justice if necessary.
Furious chairman Dave Whelan fumed: 'The OFT ruling makes me wonder what is happening to justice in this land. JJB Sports have supposedly been found guilty by a kangaroo court, without one shred of evidence against us.'
JJB Sports was one of 10 businesses, including retailers Allsports, Blacks, Sports Soccer, JD Sports and Sports Connection, to be fined a total£18.6 million.
The OFT found they made agreements to fix the price of Umbro replica football shirts in breach of competition law.
Simon Bentley, chief executive of Blacks, when the price fixing took place, said: 'If retailers are found to have been price fixing then they have to accept punishment.'