Errani, who has won nine singles titles, reached the singles final of the 2012 French Open and won five doubles grand slam titles, will be able to return to competition on October 3.
She has also been retroactively disqualified from events that took place from February 16 through June 7.
The 29-year-old pleaded not guilty after testing positive for letrozole in February, blaming the results on cross-contamination with a medicine taken by her mother.
“I feel extremely frustrated, but I'm at peace with my conscience,” she wrote on Twitter.
“I have never taken a banned substance. That substance is in a medicine that my mother has taken since 2012 and is present in our home. The only hypothesis is food contamination.”
The substance falls under the hormone and metabolic modulators section of WADA's prohibited list.