The suspension also covers Uruguay's next nine international matches, meaning the country's best offensive player is ruled out for the rest of the World Cup in Brazil and for the start of the Premier League season.
Suarez, who plays professionally for Liverpool, was also fined 100,000 Swiss francs ($112,000 US).
Suarez and the Uruguay football federation can appeal the sanctions, but Liverpool can not be formally involved in any legal challenge, FIFA spokeswoman Delia Fischer said.
Uruguay advanced to the knockout stage by beating Italy 1-0 on Tuesday in Natal, Brazil. One minute before the decisive goal, Suarez clashed with Chiellini and was caught by television cameras apparently biting his shoulder.
Match referee Marco Rodriguez of Mexico appeared not to see the incident and took no action.
"Such behaviour cannot be tolerated on any football pitch, and in particular not at a FIFA World Cup when the eyes of millions of people are on the stars on the field," Claudio Sulser, chairman of the FIFA Disciplinary Committee, said in a statement. "The Disciplinary Committee took into account all the factors of the case and the degree of Mr. Suarez's guilt in accordance with the relevant provisions of the code."
Suarez, 27, has previously been suspended by professional leagues in the Netherlands and England for biting opponents.
The high-scoring striker didn't confirm or deny biting Chiellini, but said he was angry that the Italian defender had hit him in the eye during the game.
"These are things that happen on the pitch, we were both in the area, he thrust his shoulder into me," Suarez said in Spanish. "These things happen on the pitch, and we don't have to give them so much [importance]."
Uruguay faces Colombia in the round of 16 on Saturday (CBC, CBC.ca/FIFAWorldCup, 3:30 p.m. ET).