Following the Anglo-Soviet invasion of Iran and the abdication of the Reza Shah in September 1941 and until the appointment of Mohammad Ali Foroughi as Court Minister in on March 1942, Nassrollah was "fully in charge of the court" and developed close ties with Mohammad-Reza Shah. His ministerial career began in January 1943 with an appointment as Health minister in the Cabinet of the Prime Minister Ahmad Qavam. Thereafter he successively served first as Minister of Post, Telegraph, and Telephones and as Minister of Roads in the second cabinet of the Prime Minister Ali Soheili from February 1943 to March 1944. He owed his ministerial position to royal favor and to the desire of Prime Ministers to placate the Shah He was reappointed Minister of Roads and soon made Minister of Foreign Affairs in the Prime Minister Morteza-Qoli Bayat's cabinet from November 1944 to April 1945, but he resigned in March 1945, joining the Iranian delegation at the San Francisco Conference, which established the United Nations. He served as a member and later head of the Iranian delegation at the United Nations in New York. From 19 June 1950 until 22 September 1952 he was Iran ambassador to the United States. He also served as the President of the fifth session of the United Nations General Assembly in 1950. He was, however, eventually removed from his Ambassadorial post in Washington D.C., and replaced by Allah-Yar Saleh because he did not fully enjoy the confidence of then Prime Minister Mohammad Mosaddegh
Other duties
Following the Iran coup of August 1953 he was reappointed Ambassador to the United States and served until his replacement by the cabinet of the Prime Minister Ali Amini who was lobbying a little too obviously for the premiership. In February 1958 Nasrollah was appointed Ambassador to France, where he stayed until April 1962. In July 1962 he was appointed Minister without Portfolio in the cabinet of the Prime Minister Asadollah Alam with whom he had maintained close ties. He was elected Chairman of the Inaugural Congress of the Rastakhiz Party that the Shah had created, as the single permissible party—a development interpreted as a sign of the declining power of Alam's rival, Prime Minister Amir-Abbas Hoveida. According to a 1963 report by the United States Embassy, the Entezam brothers were active members in an informal gathering which was formed around Amini and met every Wednesday for over twelve years. Like other members of Amini's Cabinet, the Entezam brothers were active participants in a number of other such gatherings. The two brothers were, however, very different in character and disposition. The flamboyant and sartorially elegant bachelor, Nasrollah also considered to be a capable official but devoid of those qualities which accounted for the prestige and respect accorded to his brother
Retirement
Entezam retired from public office in the late 1960s but was continually serving the Shah in one capacity or another. His final duties were the chairman of the United States Bicentennial celebration and co-chair of the Rastakhiz Party. He was arrested in 1979 after the Islamic revolution and died shortly after his release.
