Seihō was born in Kyoto. As a child, he loved to draw and wanted to become an artist. He was a disciple of Kōno Bairei of the Maruyama-Shijo school of traditional painting. In 1882, two of his works received awards at the Naikoku Kaiga Kyoshinkai (Domestic Painting Competition), one of the first modern painting competitions in Japan, which launched his career.

During the Exposition Universelle in Paris (1900), he toured Europe, where he studied Western art. After returning to Japan he established a unique style, combining the realist techniques of the traditional Japanese Maruyama–Shijo school with Western forms of realism borrowed from the techniques of Turner and Corot. This subsequently became one of the principal styles of modern Nihonga. His favourite subjects were animals -often in amusing poses, such as a monkey riding on a horse. He was also noted for his landscapes.

From the start of the Bunten exhibitions in 1907, Seihō served on the judging committee. In 1909 he became a professor at the Kyoto Municipal College of Painting (the forerunner to the Kyoto City University of Arts). Seihō also established his own private school, the Chikujokai. Many of his students later went on to establish themselves as noted artists, including Tokuoka Shinsen and Uemura Shōen.