Hun Sen said the decision was made at the request of Cambodian Interior Minister Sar Kheng, without giving further details.
It is the fourth Senate election originally scheduled for January 14, 2018.
Founded in 1999, the Senate has 61 seats, but only 57 senators will be elected, as two senators are appointed by King Norodom Sihamoni and the other two by the parliament's lower house.
In the last election held in January 2012, Hun Sen's ruling Cambodian People's Party won 46 seats.
Earlier on October 20, the Cambodian Senate adopted four amended and supplementary election laws which were ratified by the parliament on October 16. BY VIETNAMPLUS.
