The prime minister is accompanied by his wife.
He will be in Phnom Penh from today, Thursday, to Sunday.
Cambodia, which is the Asean chair until the year-end, has organised the summit under the theme of Asean Addressing Challenges Together.
The key points of discussion will be how Asean members can together cope with public health and economic challenges and build opportunities for sustainable development.
Asean leaders will also discuss peace and security in the region.