Officials are patrolling nightclubs in the capital Seoul to make sure they adhere to social distancing rules and are advising people to host Halloween parties online, Park Yoo-mi, a general director of the city government, told a briefing on Friday.
"Don't end up a real ghost while enjoying Halloween," reads the caption on one poster in Seoul.
Another warned this year's party "could really turn scary."
South Korea has been praised for quick and effective action against the pandemic but saw a resurgence in cases in May after an outbreak linked to nightclubs and bars in Seoul.
Seoul's government has dispatched officials and police to 153 nightclubs in the city ahead of the weekend to make sure facilities follow strict guidelines and visitors log in names and use quick response (QR) code systems for contract tracing, said city official Park.
Some 14 nightclubs have already been shut after failing to adhere to social distancing guidelines and for having more people than are allowed at nightclubs, Park said.
"The city plans to reap immediate results from prevention measures by ordering a two-week ban on gatherings for the facilities that violate the guidelines," she added.
Park urged other businesses to join the 85 night venues in Seoul which have said they would voluntarily shut their doors during Halloween to protect against the spread of the virus.
South Korea has used aggressive testing and contact tracing in a bid to contain the virus, which has infected 26,385 people and killed 463 in the country, according to the latest data from the Korea Disease Control and Prevention Agency. Daily cases have hovered around 100 over the past week.