Saul 'Canelo' Alvarez has been banned for six months after failing two drugs tests earlier this year.
The Mexican middleweight, 27, said eating contaminated meat was the reason he tested positive for clenbuterol on 17 and 20 February.
He was forced to withdraw from a world middleweight title rematch against Gennady Golovkin after their first bout in September ended in a draw.
Alvarez's ban has been backdated, so he will be free to fight from 17 August.
Golden Boy Promotions said Alvarez "looks forward to returning to the ring in September for Mexican Independence Day weekend".
The fighter, who did not attend the Nevada State Athletic Commission hearing in Las Vegas on Wednesday, said earlier this year he was "surprised and bothered" by the adverse test findings.
Alvarez's promoters said meat contamination had "impacted dozens of athletes in Mexico over the last years".
The hearing panel voted to hand down a one-year ban, reduced to six months because Alvarez had cooperated with their investigation.
Clenbuterol is used to treat asthma but can also help build lean muscle mass and burn off fat. It is sometimes illegally mixed into livestock feed to make meat leaner.
Daniel Eichner, director at the World Anti-Doping Agency-accredited laboratory that conducted the tests, said at the time: "These values are all within the range of what is expected from meat contamination."
Alvarez has won 49 and drawn two of his 52 fights. His only defeat came against Floyd Mayweather in 2013.