Chafa, who plays for Harare club Dynamos, tested positive for the banned substance prednisone, a glucocorticosteroid, the world governing body said in a statement.
The 22-year-old's ban, which includes domestic matches, was backdated to start on Aug. 30, the day he was provisionally suspended.
Dynamos' chairman Kenny Mubaiwa told Zimbabwean media in September that the substance might have been present in medication that Chafa took after sustaining a jaw injury in a league match.
Chafa is the fourth player to fail a doping test during the World Cup qualifying competition.
Peru's Joel Sanchez was banned for two years, Jamaica's Jermaine Hue for nine months and Morocco's Hamza Abourazzouki for six months.
Meanwhile, Tahiti's Vincent Simon was banned for six months for failing a doping test at the Confederations Cup in June.
- Sports & Recreation