Whyte was left devastated after an "adverse finding" from his random dope test by the Voluntary Anti-Doping Association led to the cancellation of a heavyweight fight with former world champion Joshua scheduled for August last year.
However, an investigation has revealed he was the victim of contamination of a nutritional supplement, according to Sky Sports.
The broadcaster said it had seen documentation which showed a forensic expert concluded Whyte was the "victim of a contaminated supplement that did not disclose (the contaminant) among its ingredients."
Reuters was not able to independently verify the details of the investigation.
Whyte trains in the United States and is licenced by the Texas Department of Licencing and Regulation, who were not immediately available to comment.
Whyte, who lost a title challenge to WBC world champion Tyson Fury in April 2022, said he was "angry and disappointed" and had spent a long time trying to piece together where he had gone wrong with his diet.
"It's been really tough because I knew I was innocent, but then you can't talk, you can't say anything," Whyte told Sky Sports.
"You have to be professional, trust the process, trust the lawyers and trust the people around you. It's been tough, but tough times make tough men.
"I'm relieved more than anything, but of course, I'm angry as well because it's cost me so much.
"The most important thing is it cost me the chance to beat AJ (Joshua). Everything else after that is secondary, but you know it's a mix of emotions."
Joshua eventually went on to beat Finnish stand-in Robert Helenius with a seventh-round knockout.
Whyte also said he was seeking damages from the company that manufactured the supplement.
"I've lost a lot of money and we're seeking damages for all the money I've lost, try to get some sort of redemption for my career," he said.
