A further posting as Third Secretary followed in Calcutta (1953–1956). During this time he married, at Rangpur on 5 January 1956, Mahfuza Banu of Dhubri, Assam daughter of Shahabuddin Ahmed, a respected lawyer and Mashudaa Banu a well known social campaigner. Then promoted to Second Secretary, he served in the Pakistan Embassy in Washington, D.C. from 1956 to 1960, during which time he and his wife had their two sons, one of whom went on to become a magician and corporate entertainer, Eenasul Fateh.
Fateh was a Director attached to the Foreign Ministry in Karachi from 1960 to 1963, during which time he went for a year and a half (1962–1963) to Geneva as a Fellow of the Graduate Institute of International Studies (Institut Universitaire des Hautes Etudes Internationales) under a Carnegie fellowship.
Further foreign postings followed. He was First Secretary (and latterly acting chief of mission) in Prague from 1965 to 1966, Counsellor in New Delhi from 1966 to 1967, and Deputy High Commissioner in Calcutta from 1968 to 1970. He received his first posting as Ambassador, at the Pakistan Embassy in Baghdad, in 1970.
At about the same time, in July 1971, Fateh received a summons from the Pakistan Foreign Ministry to attend a conference in Tehran of regional Pakistani ambassadors. He chose to take his official car ostensibly to drive to Tehran but, as he and his driver approached the Iran-Iraq border, he feigned chest pains and ordered the driver to return him home, where he arrived that evening. Saying that he would take a plane the next day, he dismissed the driver. That night, he fled with his wife and sons across the border into Kuwait, from where they took a plane to London.
The announcement of Fateh's defection to the Bangladesh cause marked the first time a full ambassador had joined the fledgling Bangladesh diplomatic service. The news was received with fury by the military regime in Islamabad, which meanwhile had discovered that on the afternoon just before his supposed departure for Tehran, he had cleared out the Pakistan Embassy bank account in Baghdad to the benefit of the Bangladesh government. The military regime's requests to extradite him from London were rebuffed by the British Government. These events were chronicled in a 2003 National Geographic Channel television documentary, Running for Freedom.
The Mujibnagar government made him ambassador-at-large, followed in August 1971 by the concurrent position of Advisor to the Acting President, a position he was to resign in January 1972 after the return to Bangladesh of Bangabandhu Sheikh Mujibur Rahman. He had a leading role, as the Bangladesh movement’s senior-most diplomat, in a delegation under Justice Abu Sayed Choudhury which went to the United Nations in New York to lobby for the Bangladesh cause. He was also in communication with other governments, such as the Nixon administration in the United States via the French consul. He was one of the first high officials to reach Dhaka after its liberation, and was quartered with other senior officials in Bangabhaban until January 1972. Already the effective head of the incipient foreign service, he became Foreign Secretary at the end of 1971.
In mid-1975 he was selected to be High Commissioner in the UK, which post he took up in early 1976. His two years in London (1976-1977) saw him Chairing the Commonwealth Conference on Human Ecology and Development and the Bangladesh government approved his recommendation that dual citizenship be permitted. Many people from Bangladesh were settled in the UK, whose remittances into Bangladesh were an important source of foreign exchange. He pointed out that to oblige them to forgo Bangladesh citizenship if they took up the benefits of British nationality was not conducive to the continued maintenance of their ties to the mother country.
His last post was as Ambassador in Algiers (1977–1982). He represented the Bangladesh government at conferences on Namibia in Algiers of the United Nations (1980) and the Non Aligned Conference (1981).
On 23 March 2008 Abul Fateh is mentioned by several Bangladeshi television channels for his role in 1971 war.