The Vasco Da Gama player has successfully overturned his suspension but may face further trials if the regulatory body appeals his case
The 28-year-old was reprimanded after testing positive for use of the diuretic hydrochlorothiazide - which can be used to mask the use of doping - on March 2.
The Court of Justice for Rio Sport (TJD-RJ) ruled in favour of the Brazilian attacking midfielder, though an appeal from the prosecution remains a real possibility.
Alternatively, the Court of Arbitration for Sport (CAS) in Switzerland could choose to get involved, which could see his most recent acquittal overruled and he could be suspended for up to two years.
Alberto was emotional after hearing that he would be acquitted of doping and stressed his belief that the result vindicates his protests that he is innocent.
"All these years as an athlete - serving the sport, never even got a warning from the Commission for Doping - I always respected all that was passed," he said in a statement at a press conference.
"Any professional must have an ethos and I have mine as a competitor. I have never needed or used substances to enhance my performance. My career speaks for itself."
Alberto has previously played for Werder Bremen and won five caps for the Brazil national team between 2003 and 2005.