It said the suspension will go from January 24 to 27.
The department added that the Kwai Chung Post Office will be shut during the period.
More than 100 people linked to Kwai Chung Estate have tested positive for Covid-19, prompting the authorities to seal off two blocks there for five days and conduct mass testing for residents there.
Hongkong Post said mails addressed to the affected area will be delayed and apologised for the inconvenience caused.
Nearby residents have been advised to use the Kwai Fong and Kwai Shing post offices instead.