Sihamoni, 73, departed for Beijing for health checks earlier this year and shared his cancer diagnosis in April.

The king has been receiving treatment from Chinese doctors in Beijing after undergoing "successful" surgery, according to the Royal Palace in Phnom Penh.

In a statement on Tuesday, the palace said the king's health was "getting better" after more than three months of treatment.

Sihamoni touched down in Phnom Penh on Friday afternoon and was greeted by senior Cambodian officials, including influential former leader Hun Sen and his son Hun Manet, the current prime minister, according to state-run TVK.

The king has "arrived in the country safely", Hun Sen said in a post on his Facebook page, which also broadcasted the arrival of the monarch at the airport.

A lifelong bachelor who speaks Khmer, French, Czech and English, Sihamoni spent most of his adult life abroad pursuing a career in the arts before taking the throne in 2004.

He took over the role after his father, king Norodom Sihanouk, abdicated following his own cancer treatment in Beijing. King Norodom Sihanouk died in 2012.