Hans Siegwart was born on 14 March 1925 in Küssnacht am Rigi.
After his grammar school education and several years of professional life, Hans Siegwart took up his studies at HSG at the age of 26. In 1954 he graduated with a teaching diploma after which he attended doctoral seminars for two semesters. Between 1955 and 1960, Hans Siegwart worked in a managerial position while writing his doctoral thesis. He published it in 1959 under the German title Der Einfluss der fixen Kosten auf die Unternehmenspolitik (The influence of fixed costs on corporate policy).
In 1960 Siegwart took up a position at the HSG Institute of Management & Strategy and two years later he also started to teach here. In 1963 Siegwart was appointed Head of the Business Consulting Department at the Institute of Management & Strategy and in 1965 he became Vice-Director of the Institute.
In 1966 he published his habilitation thesis under the German title Die optimale Produktionsprogrammgestaltung in industriellen Klein- und Mittelbetrieben (Best production planning for small and medium-size manufacturing companies). The following year Siegwart was appointed Full Professor of Business Administration with special emphasis on industrial production (and later accounting). He also became director of the Institute of Management & Strategy and was responsible for HSG's building and facility management.
As HSG’s President (1972 – 1978), Hans Siegwart successfully navigated the school through the changes such as change in the school’s sponsorship, the revision of its statutes and the introduction of a law degree programme. Although in 1973, the citizens of St. Gallen voted once again against the plans of further expansion of the university premises, it was thanks to Siegwart's political intuition and negotiating skills that he was able to convince the citizens of the canton to restructure the funding of the university in 1976. As a result, the main responsibility for the university went to canton, taking the main financial burden off the city of St. Gallen. The new policy came into effect at the beginning of 1977.
Siegwart was President of the St. Gallen Foundation for International Studies between 1974 and 1995 and was strongly committed to the ISC Symposium. He also served as President of the Rectors' Conference of the Swiss Universities (1983-1987) and was President of the Executive Education Committee at HSG.
Hans Siegwart was one of the founders of the Management Centre and Controlling Centre St. Gallen. As a scientist, he made a significant contribution to the development of the fields of accounting and controlling. Siegwart retired in 1990.
He died on 24 January 2003 in St. Gallen.