Barcelona have failed in their bid to overturn a FIFA transfer embargo and will be unable to sign players next year.
FIFA announced in April that the Primera Division club would be barred from bringing in anyone for two transfer windows due to concerns over the "international transfer of minors", but Barcelona appealed against the decision.
The Spanish club recruited players including Luis Suarez this summer, while their suspension went on hold during the appeals process.
However a statement from FIFA on Wednesday read "The FIFA appeal committee has decided to reject the appeals lodged by Spanish club FC Barcelona and the Real Federacion Espanola de Futbol (RFEF) and to confirm in their entirety the decisions rendered by the FIFA disciplinary committee in the respective cases relating to the protection of minors."
Barcelona immediately announced on their website plans to take their case to the Court of Arbitration for Sport, in a final challenge to FIFA's ruling.
The Nou Camp club signed five players this summer, including Suarez from Liverpool.
FIFA's statement added: "Barcelona is to serve a transfer ban which will see the club prevented from registering any players at both national and international level for two complete and consecutive transfer periods, starting with the next registration period (January 2015) given that the appeal of the club had been granted suspensive effect by the chairman of the FIFA appeal committee.
"FC Barcelona has also been ordered to pay a fine of CHF 450,000 (€371,730) and been given a period of 90 days from today in which to regularise the situation of all minor players concerned."
Barcelona were found guilty of breaching FIFA's rules on the transfer of players aged under 18.
The players in question were registered and participated in competitions with the Catalan club between 2009 and 2013, while the Spanish Football Federation (RFEF) was also sanctioned by FIFA for the same breaches.
The RFEF also saw its appeal turned down on Wednesday and has been fined.
FIFA's statement added: "The RFEF has been ordered to pay a fine of CHF 500,000 (€413,034) and granted a period of one year in which to regularise their regulatory framework and existing system concerning the international transfer of minors in football."