New cases of critically ill patients and deaths also hit record highs while an additional three confirmed cases of the omicron variant were reported to bring the total cases in the country to nine, Yonhap news agency reported.
The daily new Covid-19 cases included 5,327 local infections, raising the total caseload to 467,907, according to the Korea Disease Control and Prevention Agency (KDCA).
Saturday's total infections mark the highest number since the country reported its first COVID-19 case in January 2020 and exceeds the previous record of 5,226 reported Thursday.
The number of critically ill patients came to 752, up 16 from 736 on Friday, while the death toll came to 3,809, up 70 from a day earlier. The fatality rate stood at 0.81 per cent.
Of the locally transmitted cases, Seoul reported 2,268 new cases, and the surrounding Gyeonggi Province posted 1,671.
The number of cases from overseas came to 25, raising the total to 15,842.
Of the nine confirmed cases of the omicron variant, four came from overseas and five were local infections.
The country's first confirmed cases of the variant were discovered in a fully vaccinated couple who returned home from Nigeria last week.
Health authorities are worried about a possible community infection involving the variant, with tests currently under way on over 400 people who attended the same church service in Incheon, 40 km west of Seoul, as family members of one of the nine infected.
The confirmed cases of the omicron variant pushed the government to tighten its eased rules that began last month under the "living with Covid-19" scheme.
Starting Monday till January 2, the maximum number of people at private gatherings will be cut to six in the greater Seoul area and eight in other areas, from the current 10 and 12.
Visitors to high-risk businesses, including saunas, pubs and gyms, have to show vaccine passes or a negative test result.
Restaurants, cafes, cram schools, movie theaters, public study rooms, libraries and museums are among the newly included places.
Those aged between 12 and 18 also will be required to meet the vaccine pass measures starting February 1.
A one-week grace period for the vaccine pass system will be allowed before the rules are enforced.
Inbound travellers have to be put under a 10-day mandatory quarantine regardless of their vaccination status till December 16.
The KDCA said 42.62 million people, or 83.1 per cent of the country's population, have received their first shots of Covid-19 vaccines, and 41.28 million people, or 80.4 per cent, have been fully vaccinated.
About 3.85 million people, or 7.5 per cent of the population, have received a booster shot.