He served at the Ministry of Foreign Affairs, upon his graduation, in 1955. Afterwards, from 1959 to 1964, he acted as Secretary to Minister of Foreign Affairs. In 1964, he was appointed First Secretary of the Royal Thai Diplomatic Mission to the United Nations, New York, United States of America. In 1967, he was appointed Ambassador to the United Nations and Canada. From 1972 to 1975, he was appointed Ambassador to the United Nations and United States of America.

He returned to Thailand to resume the position of the Permanent Secretary to the Ministry of Foreign Affairs, in 1976. His last government post was Ambassador to Germany, from 1977-1978. He finally quit the Ministry of Foreign Affairs, to run Saha Union Group in 1979.

He was appointed Vice President of Thai Industry Association, in 1980, Vice President of Thai Industry Council, in 1987, and President, in 1990.

From 1982-1984, he was President of ASEAN Chamber of Commerce and Industry, and, from 1988-1989, he was President of ASEAN Task Force, in charge of ASEAN co-operation. From May 1986 to January 1991, he was President of ASEAN Committee in ASEAN-USA Council.

He also held important posts in many academic institutions, including, National Institute of Development Administration, Thailand Development Research Institute, Science and Technology Development Council, Sasin Business Administration Institute, Chulalongkorn University Council, Asian Institute of Technology (AIT) and ASEAN-USA Technology Exchange Institute. In October 1990, he was appointed Member of The World Management Council (CLOS) and, in January 1991, he was appointed Member of The Business Council for Sustainable Development (BCSD).

At Saha Union Group, he was Vice President from 1985-1990 and was appointed President, since January 1, 1991.

On March 2, 1991, he was appointed 18th Prime Minister of Thailand.

His many achievements included the following schemes: State Administration Development, Civil Officials Productivity Development, ASEAN Free Trade Area, Capital Market Promotion, Free Trade Promotion, VAT in substitution of Trade Tax, Excise Development in accordance with VAT, Private Participation in State Enterprise, World Bank Council Meeting, International Monetary Fund 46th Meeting (1991), Rural Development, Agriculture Development and Land Reform, Telephone and Telecommunication Infrastructure Projects, New Bangkok International Airport Project, Educational Opportunity Project, University Education Liberalization and Versatility Enhancement, State Enterprise Detachment from Relavant Labor Act, Natural Resource Revival and Preservation, Energy Generation and Enhancement, and Preparation for the General Election of March 22, 1992.

He left office when the General Election was held on March 22, 1992, but retained the power, until April 22, 1992, when the new government of General Suchinda Kraprayoon took office. He was re-appointed Prime Minister, once General Suchinda Kraprayoon resigned from the position, due to political and social conflicts, when the May Unrest was vigorized, on June 10, 1992, and left office when the General Election was held on September 23, 1992. He then resumed his position at Saha Union Group.

He was very active in political reform and took a very important part in the drafting of the Constitution of 1997. He received Magsaisai Awards and "Man of the Year 1997" Awards for his devotional service to the state.