In January 2012, Sihanouk issued a letter to express his wish to be cremated after his death, and his ashes are to be interred in a golden urn. A few months later in September 2012, Sihanouk said that he would not to return to Cambodia from Beijing for his 90th birthday, citing fatigue. On 15 October 2012, Sihanouk died of a heart attack at 1.20 am, Phnom Penh time. When news broke, Sihamoni, Hun Sen and other government officials flew to Beijing to pay their last respects. The Cambodian government announced an official mourning period of 7 days between 17 October 2012 and 24 October 2012, and state flags were ordered to fly at one-third mast height. Two days later, Sihanouk's body was brought back from Beijing on an Air China flight, and about 1.2 million people lined the streets from the airport to the royal palace to witness the return of Sihanouk's cortege.

In late November 2012, Hun Sen that Sihanouk's funeral and cremation was to be carried out in February 2013. Sihanouk's body laid in state at the royal palace for the next three months until the funeral was held on 1 February 2013. A 6,000-metre street procession was held, and Sihanouk's body was subsequently kept at the royal crematorium until 4 February 2013 when his body was cremated. The following day, the royal family scattered some of Sihanouk's ashes into the Tonle Sap river, while the rest were kept in the palace's throne hall for about a year. In October 2013, a stupa featuring a bronze statue of Sihanouk was inaugurated next to the Independence Monument. In July 2014, Sihanouk's ashes were interred at the silver pagoda next to those of one of his daughters, Kantha Bopha.