Gyokyo (years of his birth and death was unknown) was a Buddhist priest of Daian-ji Temple in the Heian period. His father was KI no Gyohitsu of Yamashiro no kami (the governor of Yamashiro Province). He was a secular brother of Yakushin, a priest of Ninna-ji Temple, and an uncle of Yasumune, the betto (a priest who manages the affairs of a temple) of Iwashimizu Hachimangu Shrine.
His life before entering the priesthood was unknown. He is said to have studied Hosso Sect, Sanron Sect and Esoteric Buddhism at Daian-ji Temple, but he is also said to have studied under the guidance of Gyoho, the mentor of Saicho who was the founder of the Nihon-Tendai Sect, and Soei of the Shingon Sect. Upon the recommendation of Shinga, he was dispatched to Usa-Hachimangu Shrine in Kyushu in 858 in order to pray for the enthronement of Imperial Prince Korehito (later Emperor Seiwa), a grandchild from a daughter of FUJIWARA no Yoshifusa, who married into another family. In 859, the following year, he once again confined himself for 90 days in Usa-Hachimangu Shrine to pray for the protection of the Emperor since Imperial Prince Korehito was enthroned soon after. Since he received the oracle during this period, he prayed for the coming of Great Bodhisattva Hachiman from Usa-Hachimangu Shrine to Gokoku-ji Temple at Mt. Otoko in Kyoto Prefecture, and founded Iwashimizu Hachimangu Shrine. He assumed the position of dento daihosshi (great Dharma-master who transmits the flame) in 863.