Born in 1121 (dates disputed), from Kii Province. He entered the monastery young and made three journeys to Song China, absorbing the latest Buddhist scholarship and construction techniques. After returning to Japan, he continued wandering and pilgrimage to Kumano, Koyasan, and Shitennoji. In November 1180, Taira no Shigehira's burning of Nara reduced Todai-ji and Kofuku-ji to ashes. In response, Retired Emperor Go-Shirakawa appointed the 61-year-old Chogen as chief fundraiser and project director (daikanjin) for Todai-ji's reconstruction. Chogen traveled the country soliciting donations of funds and timber, winning major support from Minamoto no Yoritomo. He brought craftsman Chen Hejing from Song China and introduced the "Daibutsu-yo" (Great Buddha style, also called "Indian style")—a powerful, bold architectural mode that had not existed in Japan. This technique is still visible in Todai-ji's Great South Gate today. The Great Buddha's eye-opening ceremony was held in 1185, and the Gate's Nio statues (by Unkei and Kaikei) were completed in 1203. Chogen continued directing the reconstruction for over 25 years until his death in 1206 at age 86.

A monk of astonishing energy and practicality. He took on the massive project at 61 and drove it for 25 years without rest. A medieval project manager with superb negotiation and organizational skills.

The Todai-ji Great South Gate and its Kongo Rikishi statues (by Unkei and Kaikei) are fruits of his work. Daibutsu-yo architecture revolutionized Japanese building. He accomplished the medieval era's greatest reconstruction.