Inyo sacaro rasmi baangkek manjadi rajo pado tanggal 29 Oktober 2004.[9] Rajo Sihamoni jo kaduo urang gaeknyo, Ayah Rajo Norodom Sihanouk jo Ibu Suri Norodom Monineath, sacaro kusuih mintak supayo acaro baralek rajo indak balansuang mewah karano mareka indak mau nagara nan miskin tu mangaluakan banyak pitiah untuak alek tasabuik.
He was inaugurated and formally appointed as King on 29 October 2004.[7] King Sihamoni and his parents, King Father Norodom Sihanouk and Queen Mother Norodom Monineath specifically requested that the ceremonies not be lavish because they did not wish the impoverished country to spend too much money on the event.