Hyoso (687–702) (r. 692–702) was the thirty-second monarch of Silla, a kingdom that flourished on the Korean peninsula from approximately 200 to 927 CE. He was the eldest son of King Sinmun and his second consort Queen Sinmok. He reigned for a decade and died of illness in the Silla capital in the autumn of 702.

Hyoso's reign was characterized by a continuing trend towards centralization following Silla's unification of the peninsula. Like his father, Hyoso faced some opposition in the form of revolts by high-ranking members of the Silla aristocracy.^[1] In the summer of 700, for instance, the ichan (a high rank in Silla's strict bone rank system) Gyeong-yeong 慶永 was implicated in treasonous plots and executed. These machinations also apparently involved Silla's Chief Minister of State, who was removed from office.^[2]

Relations with Tang also saw improvement during Hyoso's reign following the diplomatic disintegration that followed in the wake of the wars of unification during the 660s and 670s and the foundering of the Tang-Silla alliance.^[3] Tribute relations were steadily maintained and Hyoso, as Sinmun before him, was "enfeoffed" by the Tang emperor as King of Silla.

A few citations in the record of King Hyoso in the 12th century Korean history Samguk Sagi also attest to steady diplomatic contact with Japan, and Japanese histories (notably the Shoku Nihongi) are reliable sources for confirming death dates of Silla's kings and queens during this period, as Japan would often hear of their deaths through diplomatic envoys.

King Hyoso died in 702. Because he had no son he was succeeded by his younger full brother who reigned as King Seongdeok.