Walter B. Kielholz was born in 1951 in Zurich, where he grew up and completed his primary education. After studying Corporate Finance and Accounting at the University of St. Gallen, he began a career in the financial services industry. Starting at the US reinsurance company General Re with positions in Zurich, Rome, London and New York. In 1986 he joined Credit Suisse's Commercial Banking department. In 1989 he began his over 30-year career at Swiss Re, the world's largest Reinsurer, responsible for the company's Asian business. In 1996 he became the Chief Executive Officer of Swiss Re. In 2002 Walter B. Kielholz was appointed Chairman of the Board of Directors of Credit Suisse Group, which he steered through the great financial crisis. In 2009 he switched to Swiss Re as Chairman of the Board. In 2021 he retired and was appointed Honorary Chairman of Swiss Re.

Besides his professional career, Walter B. Kielholz has always been socially and culturally active in various forms. For 10 years he was the president of liberal think tank "Avenir Suisse" and for 19 years he presided over the "Zürcher Kunstgesellschaft" the patron association of the Kunsthaus Zurich.

Walter B. Kielholz is a trustee of the Carnegie Endowment for International Peace a nonpartisan international affairs think tank in Washington, DC. He is a member of the Bretton Woods Committee, a non-profit organization dedicated to effective global economic and financial cooperation, also in Washington, DC. He is also an Honorary Senator of the Lindau Nobel Laureate Meetings. In May 2021, Walter Kielholz, a long time supporter of Human Rights Watch, became Chair of the Zurich Committee of Human Rights Watch.