Born in 948 as the eldest son of Minamoto no Mitsunaka, head of the Seiwa Genji line, in Tada, Settsu Province (present-day Kawanishi, Hyōgo). His name is formally read "Yorimitsu" but is popularly known as "Raikō." He served closely under Fujiwara no Michinaga during the golden age of regency politics, establishing himself as a preeminent military leader. He held posts including Vice Master of the Left Stables, Governor of Tanba, and Governor of Mino, building the foundation of the Settsu Genji. Raikō's enduring fame rests on his demon-slaying legends, leading his four elite retainers known as the "Shitennō" (Four Heavenly Kings)—Watanabe no Tsuna, Sakata Kintoki (the model for the folk hero Kintarō/Golden Boy), Urabe no Suetake, and Usui Sadamitsu. The most celebrated tale is the slaying of Shuten-dōji, a fearsome oni dwelling on Mount Ōe in northern Kyoto, depicted in countless literary works including the Otogi-zōshi. His legend of slaying the Tsuchigumo (earth spider) demon from his sickbed became the basis of the Noh play "Tsuchigumo." Historically, he served as the military pillar of the Fujiwara regent house and played a key role in establishing the Minamoto as leaders of the warrior class. He died in 1021 at age 74. In recent years, he gained a new fan base through the mobile game Fate/Grand Order, where he appears as a female character named "Minamoto no Raikō."

A loyal warrior serving Fujiwara no Michinaga, yet bold enough to face demons without fear. He bound his elite Shitennō retainers with bonds of trust that became an ideal of lord-vassal relations.

He created the archetype of demon-slaying legends in Japan. The tales of Shuten-dōji and Tsuchigumo influenced Noh, ukiyo-e, and kabuki profoundly. His retainer Sakata Kintoki became the model for the Kintarō (Golden Boy) legend, still celebrated during Boys' Day.