Debnath Shaw joined the Indian Foreign Service (IFS) in 1984. He served in Indian diplomatic missions in Hong Kong, Beijing (twice), Bonn and Dhaka. He was Joint Secretary in the Ministries of Defence and External Affairs, respectively. He served as Ambassador of India to Azerbaijan. He was High Commissioner of India to Tanzania. He was a visiting fellow at the South Asia Programme of the Center for Strategic and International Studies (CSIS), in Washington, DC.