Seven cases were reported in the city of over 20 million people on Wednesday, including six in the southern Daxing district.
All 1.6 million residents of Daxing must not leave Beijing unless they have received special permission from the authorities and tested negative for Covid-19 in the past three days, the district said.
Meetings of 50 or more people in the district have been banned, while “weddings should be postponed and funerals simplified,” the district government said.
Officials also ordered all kindergarten, primary and secondary students in the district to study at home.
Residents of five Daxing neighbourhoods where the cases were detected were ordered to remain indoors.
The report said the virus was largely brought under control but a spate of small, localized outbreaks prompted Chinese officials to order mass testing, strict lockdowns, and to prepare to move thousands into quarantine facilities to stamp out a resurgence.
China reported 103 new cases on Wednesday, including the seven in Beijing.
The outbreaks, including in neighboring Hebei province, have put China on high alert for a potential wave of cases ahead of the upcoming Lunar New Year holiday.
This comes after nearly three million people in northeastern Jilin province were placed under lockdown on Monday after a travelling salesman infected over a hundred people.