The Centres for Disease Control and Prevention said the 43-year-old had contracted the illness after returning from Brazil and was diagnosed on Tuesday (March 22), BBC News said.
The infected man was being treated in Gwangju city and according to South Korean authorities, was later quarantined upon returning home.
Zika, a mosquito-borne virus, has been declared a global health emergency by the World Health Organization (WHO) since its rapid spread across Brazil and the Americas.
It is suspected of causing birth defects but WHO experts have urged caution on the link between the disease and microcephaly - a case where babies are born with underdeveloped heads - as it has not yet been proven.
Isolated Zika infections have already been reported in a handful of Asian countries.
