​He was the eldest son of Emperor Toba (reigned 1107-1123) and ascended to the throne at the age of 3 when Toba had been forced to abdicate by his grandfather, the retired Emperor Shirakawa. When Shirakawa died in 1129 Toba became the cloistered emperor and was the effective behind the scenes ruler through the reign of Sutoku and his two successors. Sutoku himself abdicated in 1141 and was succeeded by Konoe, the eigtht son of Toba. Since his abdication Sutoku had anticipated that his son would succeed Konoe to the throne: however, when Konoe died childless in 1155 at the age of 16, political manouvering resulted in Toba's fourth son, Masahito, assuming the office under the name of Go-Shirakawa; he reigned from 1155 to 1158.

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When Toba, the father of both Sutoku and Go-Shirakawa, died in 1156 a fierce dispute between the two brothers centring on Go-Shirakawa’s accession to and continued occupancy of the throne broke out. Go-Shirawa was supported by the regent Fujiwara Tadazane’s eldest son, while the latter’s younger brother supported Sutoku.  The Minamoto and Taira samurai clans were also drawn into the struggle, again with generational rivalries involved. Sutoku was supported by the head of the Minamoto clan, Minamoto Tameyoshi, while the latter’s eldest son, Yoshitomo, took the side of Go-Shirakawa.  Go-Shirakawa was also supported by the head of the Taira clan, Taira Kiyamori, while the latter’s uncle, Taira Tadamasa, was on the Sutoku side. Matters came to a head in July 1186 when the two sides fought a pitched battle in Kyoto, the Hōgen rebellion. The Go-Shirakawa forces carried the day.