Before the French regained control of Savannakhet in March 1946, Siphandone seized the entire provincial fund (150,000 piastres).

In 1966 he became commander-in-chief of the resulting "Lao People's Liberation Army", which fought with North Vietnamese support, in the Laotian Civil War against the royal troops.

[5] On 15 August 1991, he succeeded Kaysone as Prime Minister of Laos, who had left office to become president.

[9] His son Sonexay joined the LPRP Politburo in 2016[10] and became Prime Minister of Laos in 2022.

The Vietnamese ambassador to Laos Nguyen Ba Hung presented a birthday gift to Siphandone to his son Sonexay.