The friendly dinner was held at Moon's hotel in Cambodia, only hours after he arrived here on a three-day state visit.
Moon is the first South Korean president to make a state visit to Cambodia in 10 years.
The previously unscheduled dinner came at a last-minute suggestion from the Cambodian leader, who is also set to hold a bilateral summit with Moon on Friday.
|Moon Jae-in arrives in Cambodia (Yonhap)|
"The (dinner) schedule has been added as Prime Minister Hun Sen expressed his wish to hold a social event separate from their official talks," Moon's spokesman Kim Eui-kyeom said earlier.
The South Korea-Cambodia summit was widely expected to discuss ways to improve the countries' bilateral ties, as well as South Korea's relations with the Association of Southeast Asian Nations (ASEAN).
Moon is currently on a trip to three ASEAN countries that earlier took him to Brunei and Malaysia.
Moon is also scheduled to call on King Norodom Sihamoni during his stay here.
Before wrapping his visit on Saturday, the South Korean president will visit Angkor Wat, one of the world's oldest religious monuments.
His trip to the ancient Buddhist temple comes at a request from Cambodia, according to his office Cheong Wa Dae.
"Because Angkor Wat is a symbol of Cambodia's glorious ancient civilization and pride of Cambodians, (the president) agreed to accept the invitation to show his appreciation and respect," the Cheong Wa Dae spokesman said earlier.
He will head home Saturday, also wrapping up his weeklong tour that began Sunday. (Yonhap)