After 15 new cases on Friday, Hun Sen said the Chinese shots were needed despite his previous position that Cambodia would only use vaccines recognised by the World Health Organization (WHO).
"Many countries are already using vaccines, including those of the People's Republic of China, Sinopharm and Sinovac, which are our necessities and we cannot wait any longer," Hun Sen said in a voice message on Facebook.
"This is necessary for national defence, to prevent the people from contracting this vicious pandemic."
Hun Sen said that among those to receive vaccines would be leaders in the government, Royal Palace, National Assembly and Senate.
The nation of about 16 million people is one of the least impacted by the coronavirus with just 426 infections and no deaths, but it saw a rare cluster of cases in November.