On 10 December 1939, Sohmen was born in Linz, Austria. Sohmen grew up in Linz.
In 1958, Sohmen graduated from the Linz Realschule (Fadingerschule) with distinction. He then studied law at the University of Vienna and Southern Methodist University, and won a Fulbright scholarship to continue the University of Connecticut in the United States, eventually receiving his doctorate in Vienna.
In 1967, Sohmen married Anna Pui Hing Pao, whom he had met while studying in Canada. Sohmen has three children (two sons and one daughter).
Sir Yue-Kong Pao, Sohmen's father-in-law, owned World-Wide Shipping Group, one of the largest shipping companies in the world. In 1970 Sohmen moved with his family to Hong Kong in order to join the family Business. After periods working in Bermuda (1974) and London (1977), in 1981 he finally settled in Hong Kong. With advancing age Pao gradually stepped back from day-to-day management and in 1986 Sohmen was appointed chairman of the World-Wide Shipping Group and Pao's ownership was passed to Sohmen's wife in 1989. In 2003 World-Wide completed the takeover of Norway's Bergesen fleet to become Bergesen Worldwide Ltd., since then renamed BW Group. The group includes 140 tankers and more than 4500 employees (2010).
In 1987 he established the Egon Sohmen Foundation in memory of his brother Egon Sohmen (1930–1977). The Foundation promotes economic research and aims to get involved in important public policy debates. For this purpose it initiated its own star-studded annual international symposia and lectures at universities where Egon Sohmen formerly worked. It issued a separate publication. Scientific Advisor until 1999 Herbert Giersch, since 2002, Bernd Hans Jurgens.
With the aim of enabling young Austrians to have their first contacts with the Asian region, in 1991 Sohmen set up the Sohmen-Far East Foundation (SFEF). Operational headquarters of the advisory board of the foundation is in his home town of Linz. Qualified scholarship recipients through these grants have the opportunity to expand their horizons and to establish Business contacts.
In 1993, Sohmen established the Sohmen-China Foundation for the Promotion of Austria Society (ÖGCF) to promote friendly and cultural relations with the PRC. It supports a variety of cultural and intellectual events and supports aid for visitation programs, educational concerns, activities in Austria and the publication of relevant publications. In 1996 and 2003 in Shanghai and Beijing on Tiananmen Square, it has co-organized exhibitions.
Sohmen's wife Pui Hing Anna Pao Sohmen held several functions in Hong Kong and was also a member of the Chinese People's Political Consultative Conference. In 2005 she was awarded the Silver Bauhinia Star.
In Nov 2014, Sohmen retired as chairman of BW Group. He is replaced by Andreas Sohmen-Pao, one of his sons.