Suarez and the Uruguayan Football Association challenged the ban - and a nine-match international suspension - handed out after the striker bit Chiellini during his country's World Cup game against Italy.
Uruguayan FA president Wilmar Valdez called the sanctions "totally exaggerated", but FIFA's Appeal Committee has now upheld the original decision.
A FIFA statement read: "The Appeal Committee has decided to reject the appeals lodged by both the Uruguayan player Luis Suarez and the Uruguayan FA, and to confirm the decision rendered by the FIFA Disciplinary Committee on 25 June 2014 in its entirety.
"The terms of the decision taken by the FIFA Appeal Committee were communicated to the player and the Uruguayan FA today."
Suarez, who is expected to leave Liverpool for Barcelona in the near future, can still take his case to the Court of Arbitration for Sport.
FIFA head of media Delia Fischer added: "The relevant decision is not yet final and binding, i.e. an appeal to the Court of Arbitration of Sport is still possible by the player and/or the Uruguayan FA, subject to certain conditions."
The disciplinary committee's initial decision took into account there had been no remorse from Suarez, and the fact it was the third time he had been involved in biting an opponent.
After lodging his appeal, Suarez did then issue a formal apology to Chiellini and vowed never to bite anyone again.
Claudio Sulser, the head of FIFA's disciplinary committee, said last week: "The player cannot have any activity related to football, but a medical examination for a transfer, yes - the sanction is not linked to transfer rights."
Asked why the committee imposed a ban that damaged Liverpool, Sulser said: "That's your opinion. It's a sanction against the player. That is the risk if you are a player and you are sanctioned at the World Cup.
"I agree with you it's a problem for Liverpool, but the sanction is in the disciplinary regulations."
Sulser added that the Suarez bite was "a very severe case" but that the sanctions - which also included a nine-match international ban and a £66,000 fine - were not to set an example, but for "justice".
"This is still an ongoing case and an appeal has been filed, so I prefer not to give my opinion,” he added.
"When the committee was analysing this case, one thing I mentioned in my capacity as the chairman is we don't need to impose an exemplary sanction, we need to have justice and reached the sanction in a very severe case."
Suarez’s future at club level has not yet been resolved after Barcelona held talks with Liverpool last week over a deal for the striker.
But Suarez has previously been praised by Barca sporting director Andoni Zubizarreta for showing humility by apologising for his bite on Chiellini.
"Suarez has shown he is humble enough to admit an error, which is very important," Zubizarreta told reporters.
"He has been humble enough to apologise to those he has affected, because it happened in the middle of a festival of football. In this case it's the best thing a person can do."