Hundreds of thousands of Cambodians, dressed in black and white, massed before dawn to pay their respects to the mercurial monarch, who died of a heart attack in Beijing in October, aged 89.
The legions of mourners, many weeping and holding their hands together in a mark of respect, waited by the roadside as the funeral procession inched through Phnom Penh's avenues, flanked by courtiers in white traditional costume.
A father of 14 children over six marriages, Sihanouk abdicated in 2004 after steering Cambodia through six decades marked by independence from France, civil war, the murderous Khmer Rouge regime, his own exile and finally peace.
Many elderly Cambodians credit him with overseeing a rare period of political stability in the 1950s and 1960s, following independence, until the Khmer Rouge emerged in the 1970s.
Up to 2 million people died under their reign of terror, including five of Sihanouk's own children, but even though the ever-changeable monarch had allied himself with the Maoist movement, he never lost his people's veneration.
"He did great things for the country. I love him very much. I'm really sad that we've lost him," 70-year-old Suon Toch said as he waited near the palace with his family, holding a portrait of the late royal.
Sihanouk's widow Monique, dabbing her teary eyes, walked behind the golden casket as it was brought out of the royal palace in Phnom Penh, accompanied by their son king Norodom Sihamoni.
A 101-gun salute marked the start of the elaborate procession to honour the ex-king, who was placed on the throne by the French at the age of 18 but swiftly developed into a canny political survivor.
With two monks riding a float shaped as a mythological bird at the head of the procession, the body of the late monarch was paraded through the capital, heading for a specially built crematorium in a city park.
Sihanouk - a self-confessed "naughty boy" who loved to direct films, write poetry and compose songs - remained hugely popular among Cambodians, but his record is not without controversy.
After being ousted by the US-backed General Lon Nol in 1970, he aligned himself with the Khmer Rouge, only to be placed under house arrest as the communist regime terrorised the nation.
Before the Vietnamese toppled the Khmer Rouge in 1979, Sihanouk took exile in China, regaining his throne in 1993, although his influence was greatly diminished.
Observers say Sihanouk's passing is likely to further diminish the influence of the monarchy in a country that is now at peace but dominated by strongman prime minister Hun Sen, whose government is regularly accused of suppressing political freedoms and mistreating rights campaigners.
In contrast to his father, Sihamoni has taken a quieter role in Cambodian life since ascending to the throne in 2004, preferring to carry out his ceremonial duties rather than engage in the political jousting that characterised Sihanouk's reign.
"Sihamoni is childless. The royalist party is in shreds," said historian and Cambodia expert David Chandler.
Mr Chandler said ordinary people "loved Sihanouk, to an extent, and I think elderly people like the idea of there being a king, but Hun Sen and the younger generations couldn't care less".
For the past three months Sihanouk's body - embalmed with the help of Chinese experts - had been lying in state in the royal palace, where foreign leaders and members of the general public paid their respects.
It will be kept at the cremation site for religious ceremonies until Monday when his wife and Sihamoni are expected to light the pyre.
Foreign dignitaries including French prime minister Jean-Marc Ayrault, Japan's Prince Akishino and a host of Asian leaders and high-ranking officials are due to attend the cremation.
After the cremation, Sihanouk's remains will be put in a gold-coloured urn that will be placed in a stupa inside the royal palace, in line with his wishes.