After a brief stint in the family business and at a bank, he joined the Indian Foreign Service (IFS) in 1984. After a stint at the Ministry of External Affairs (MEA), New Delhi, he served in Indian diplomatic missions in Hong Kong, Beijing (twice), Bonn and Dhaka. He was a visiting fellow at the South Asia Programme of the Center for Strategic and International Studies (CSIS), in Washington, DC in 2004-05. He was Joint Secretary in the Ministries of Defence and External Affairs, respectively, from mid-2005 to end 2008. He served as Ambassador of India to Azerbaijan at Baku, December 2008 to May 2012. He was High Commissioner (Ambassador) of India to Tanzania at Dar es Salaam, July 2012 to July 2015. He retired from the IFS on 31 July 2015.

Post retirement, Debnath Shaw was engaged by the Ministry of External Affairs (MEA), New Delhi as Consultant for the India-Africa Forum Summit (IAFS- III) held in New Delhi in October' 15. From March 2016 to September 2020, he was engaged as Advisor (Business Development) to WAPCOS Limited, New Delhi, particularly for liaison work for the Company's overseas business. Currently, he writes on foreign affairs and security issues for journals/publications of MEA and IDSA and a few other online publications. He also advises and assists businesses in India seeking overseas markets and businesses, particularly in the countries and regions he has worked in.

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