The Italian Olympic Committee (CONI) confirmed in a statement that its anti-doping panel had annulled the preliminary ban which was imposed on Dec. 13.
Acerbi, who was treated for testicular cancer in July when he had a tumour removed, failed the doping test after the match against Cagliari on Dec. 1.
Sassuolo subsequently issued a statement blaming the positive result on traces of the hormone human chorionic gonadotropin (HCG) which is produced by some cancerous tumours.
"This is an outcome which brings serenity and distances Acerbi from the shadow of indulging with prohibited practices, something which he has never adopted," the player's lawyer Mattia Grassani told Gazzetta dello Sport.
"Justice has been done and now Acerbi can concentrate exclusively on receiving medical care to get over his illness as soon as possible."
The 25-year-old central defender, who spent the first half of last season at AC Milan, joined promoted Sassuolo from Genoa before the start of the season and the tumour was discovered during a routine medical.
Before Christmas, Acerbi thanked the club and its supporters for their backing.
"I want to thank you all, one by one," Acerbi said on his Twitter account. "You give me the strength to face this difficult moment with courage and hope. Thank you from the heart.
"A very special thanks to my team mates, the directors and the doctors at Sassuolo who are doing everything possible to help me."