Tony Yoka - known as "the French Anthony Joshua" - has been banned from competition for a year by the French anti-doping agency following three no-shows at anti-doping tests between July 2016 and July 2017.
Yoka - a super heavyweight gold medalist at Rio 2016, like Anthony Joshua four years earlier - is often compared to the British champ.
The 26-year-old turned professional straight after the Olympics with the aim of winning the heavyweight world title in the coming years.
The ban is a serious setback for the Frenchman who won his first five professional fights.
"It's a professional mistake. There was negligence on my part, especially after the Olympics," said Yoka. "There has never been any medication taken."
The boxer who trains in California will be allowed to compete abroad but said he's not interested in doing so.
"I want to bring the first world heavyweight championship belt [to] my country."
In 2010, Yoka beat Joseph Parker in the final of the Singapore Youth Olympic Games.
At the Rio Olympic Games he formed a 'golden couple' alongside his wife Estelle Mossely who won a gold medal in the women's under 60 kg. They have a son named Ali, in tribute to the boxing legend Muhammad Ali.