Officials said the four were found to carry the virus by arrival testing at the airport, triggering the flight ban from Thursday to December 29.
They were among the 10 new imported coronavirus cases reported in Hong Kong on Thursday.
Meanwhile, authorities are investigating the infection of a 51-year-old woman who tested positive after travelling to Taiwan.
The patient, who lives at Silver Waves Court in Mui Wo, tested negative before she flew to the island on December 2.
She developed symptoms on December 11 and tested positive the following day.
“As a prudent measure, the places where the patient visited in Hong Kong during the incubation period have been included in a compulsory testing notice,” health officials said.