Born in Shiga Prefecture, Uno enrolled in the Kobe College of Commerce before he was conscripted into the army during World War II.

In 1960, he entered politics and was elected to the National Diet, becoming a leading Liberal Democratic Party member and a key ally of Yasuhiro Nakasone.

[2] As well as a politician, Uno was an accomplished writer, who wrote a book considered classic in Japan about his experiences as a prisoner of war in Siberia.

Uno encountered public scandal in 1989, when accused by the Geisha entertainer Mitsuko Nakanishi[5][6] of being "immoral" and ungenerous in his financial support during their four-month affair in 1986.

She later remarried another man and divorced, attended a Shingon Buddhist school temple in Shiga Prefecture, and held various secretarial jobs unrelated to the geisha community.

To avoid further scandal, Sōsuke Uno resigned as prime minister on 10 August 1989 after just 68 days in office, but continued to serve his country in various government posts until he retired fully in 1996.

On 29 April 1994, he was awarded with the highest possible honour for an ordinary civilian, the Grand Cordon of the Order of the Rising Sun with Paulownia Flowers.