He was appointed professor at the University of Oslo from 1934. Among his works are his thesis Grundrentelæren from 1917 and Die Wertungslehre from 1923. In addition to his academic career, Keilhau also engaged in other activities.
He published two novels and a poetry collection.
He was Chief Executive Officer of Norway"s first airline company, Det norske Luftfartsrederi, in 1918.
During World World War II he was a member of the board of directors of the London department of Norges Bank.
