He began his studies in 1938, and at the University of Leiden he completed the training course for the Indonesian Civil Service.
In 1968, he took up the Japanese Chair in the Ostasiatisches Seminar at the University of Zürich, a position which Ouwehand held until his retirement in 1986.
In 1964, Cornelis Ouwehand published his Doctor of Letters thesis entitled Namazu-e and their Themes: an interpretative approach to some aspects of Japanese folk religion, a detailed, structuralist study of catfish images (namazu-e).
The book was translated in Japan in 1979 as Namazu-e. Minzokuteki Sôzôryoku No Sekai 鯰 絵 - 民俗的想像力の世界, by Komatsu Kazuhiko, Nakazawa Shinichi, Iijima Yoshiharu, and Furuie Shinpei.
In 1985 Ouwehand published Hateruma: socio-religious aspects of a South-Ryukyuan island culture, an ethnographic study which examines the ritual life in Hateruma, part of the Yaeyama Islands.