In 1973 Frendo graduated with a master's in history from the University of Malta, with a thesis on the language-culture clash in the 19th – 20th century between traditional italianita’ – latinita’ adherents and utilitarian assimilationist pro-English supporters and the codification of the historic and enduring Maltese language.
In 1978 Frendo accepted a position with the United Nations High Commissioner for Refugees (UNHCR) at their headquarters in Geneva, after he encountered fierce resistance to his academic work by the Labour government.
During his tenure there, Frendo was assigned to liaise in mass voluntary repatriation operations in Zimbabwe from neighbouring countries - such as Mozambique, Zambia and Botswana.
From 1985 to 1988 Frendo was a senior lecturer in European political development, Commonwealth history and lllEthnic lllStudies at La Trobe University, Victoria, Australia.
From 1996 to 1998, Frendo was chairman of the Euro-Med Group and was head of delegation to the Congress of Local and Regional Authorities of Europe (CLRAE) for two terms.
In this same year, Frendo was appointed as the Maltese Ministry of Justice and Home Affairs’ Chairman of the Refugee Appeals Board in Valletta (Malta).
In 2006 Frendo was appointed guest professor at the University of Enna (Italy) where he lectured in contemporary history and politics of the Mediterranean.