South Africa on Thursday said it would not renew temporary permits of around a quarter-of-a-million Zimbabweans working in the country when their visas expire next month.
Some 250,000 Zimbabweans fleeing political and economic crises at home were granted four-year work visas in 2009.
The visas have been repeatedly extended, but the government announced there would be no further extension, opening the potential for mass expulsion of workers.
"Cabinet decided to no longer issue extensions to the Zimbabwean special dispensations," Mondli Gungubele, a minister in President Cyril Ramaphosa's office, told a news conference.
The workers have been given a year's grace to apply for alternative visas that may be applicable to individual situations.
"At the expiry of this 12-month period, those who are not successful will have to leave South Africa or be deported," said Gungubele.
Zimbabweans are found across South Africa, working particularly in the hospitality, retail and service sectors.
South Africa, the continent's most industrialised economy, is a magnet for economic migrants searching for better job prospects in the region.
But Ramaphosa's government is under pressure to create job opportunities for its citizens as ballooning unemployment rates exceed 34 percent.
The country has in recent years been tightening its visa regulations and closing loopholes.
According to the last population census, South Africa hosts more than 2.2 million foreigners, including political refugees, economic migrants and skilled expatriate workers.