As under secretary, he oversaw the bureaus responsible for U.S. policy in each region of the world and served in the senior career Foreign Service position at the department.

Burns attended Wellesley High School,[2] and studied abroad in Luxembourg in 1973 with the American Field Service Program.

[3] Prior to entering the Foreign Service, Burns worked as program officer at A.T. International, a nonprofit organization specializing in economic assistance for Third World countries.

During this time, he attended all U.S.–Soviet summits and numerous other international meetings and specialized on economic assistance issues, U.S. ties with Russia and Ukraine, and relations with the Baltic countries.

He was special assistant to President Bill Clinton and Senior Director for Russia, Ukraine, and Eurasia Affairs.

He had lead responsibility in the White House for advising the president on all aspects of U.S. relations with the fifteen countries of the former Soviet Union.

[4] During his tenure as Ambassador, the U.S. expanded its military and law enforcement cooperation with Greece, strengthened their partnership in the Balkans, and increased trade investment and people-to-people programs.

[5] Prior to his final assignment, Burns was the United States Permanent Representative to the North Atlantic Treaty Organization.

After leaving government service Burns started working for the Cohen Group, an international business consulting firm.

[9] At Harvard Kennedy School, Burns has taught courses in diplomacy, American foreign policy, and international politics.

[12] Burns has also consulted and given paid speeches for the employees of Goldman Sachs, Bank of America, State Street, CitiBank, Honeywell, and a number of other companies, universities, and associations.

[18] Burns was involved in the June 2023 meeting between American and Chinese officials, including US Secretary of State Antony Blinken and China's Foreign Minister Qin Gang, that aimed to re-establish diplomatic communications after the bilateral relationship had worsened in preceding years and months, including after the US downing of a Chinese high-altitude balloon in February 2023.