In 1976, Choudhury became the first Ambassador of Bangladesh to the Kingdom of Saudi Arabia. He also had concurrent accreditation to Jordan and Oman. During this assignment, he represented Bangladesh in the Organization of the Islamic Conference. He served as the Foreign Secretary of Bangladesh during 1981–1982. He was appointed Ambassador to the United States in June 1982. As a member or leader of his country's delegations, he attended the United Nations General Assembly session; the Islamic Summit Conference held in Taif, Saudi Arabia (1981); the Islamic Foreign Ministers' Conference in Tripoli (1977), Dakar (1978), Fez, Morocco (1979), Islamabad (1980) and Baghdad (1981); the North-South Summit on International Cooperation and Development held in Cancun, Mexico (1981); Meetings of the Islamic Summit-level Peace Committee to resolve disputes between Iran and Iraq; the extraordinary session on Afghanistan of the Islamic Foreign Ministers in Islamabad (1980); and the extraordinary session on Jerusalem of the Islamic Foreign Ministers held in Amman (1980).