In the early Edo Period, in 1629, the founder of the Mito Tokugawa family, Yorifusa, maintained a separate Edo residence, the garden of which was completed during the reign of the second clan ruler, Mitsukuni. This garden features a central pond and hills, making it perfect for a stroll. When Mitsukuni set about constructing the garden, he incorporated some concepts of the Chinese Confucian scholar Shushunsui of the Ming dynasty, including a garden reproduction of Seiko Lake (China), a "Full Moon Bridge" and other features with cultural origins in China.
The name of the garden, "Korakuen," came from a Chinese text in Hanchuen's "Gakuyoro-ki" admired by Mitsukuni which said that there is "a need for those in power to worry about maintaining power first and then enjoy power later." Thus, the name Korakuen, meaning "the garden for enjoying power later on," was chosen.
Under the terms of the Law for Preservation of Cultural Assets, Koishikawa Korakuen has been designated an important historical asset and site of special historical significance. This double designation has been given only to such important sites as Koishikawa Korakuen, Hama Detached Palace, Kinkakuji, etc.