Koo was a businessman at the time of the Treaty of Shimonoseki in which Qing dynasty China ceded Taiwan to Japan. When the Japanese forces arrived in Taiwan in 1895, Koo initiated contact with the Japanese forces in Keelung and urged them to enter Taipei to restore order.
Koo's close links to the Japanese allowed him both to pursue a successful political career (he became the first Taiwanese to be appointed by the emperor to the House of Peers of Japan, in 1934) and to build a collection of businesses that formed the nucleus of today's Koos Group of companies.
Koo had four concubines, eight sons and four daughters. His fifth son, Koo Chen-fu, inherited control of his father's business and served as the negotiator for Taiwan during the talks with China in 1993 and 1998. His eighth son, Koo Kwang-ming was and is a leader of the Taiwan Independence movement. His grandson is Richard Koo, an economist specializing in balance sheet recessions.