After completing high school in 1947, he enrolled in general history undergraduate study at the University of Zagreb, from which he graduated in 1952. In the same year he took up an assistant position at the Faculty of Philosophy, University of Sarajevo. He conducted research in archives in Zagreb, Belgrade, Zadar, and Vienna in Austria. He received his doctorate in history from the University of Zagreb in 1958 upon defending his dissertation entitled The uprising in Bosnia from 1875 to 1878, which has been published in three editions and translated into German. He visited Princeton University for one year, and then continued his academic career as a professor of history at the University of Sarajevo where he worked as a full professor from 1968 until 1992 teaching "General History of the New Age" and "Introduction to the Science of History'" courses. Shortly after the outbreak of the Bosnian War in 1992, he was arrested by the government-loyalist Green Beretsparamilitary unit along with his family. Initially held in house arrest at the elementary school in Vratnik, he was released and managed to flee to Bosnian Serb-controlled proto-state known as the Republika Srpska. From 1992 to 1994 he worked as a full professor at the Faculty of Philosophy, University of Belgrade. He retired on 1 October 1994. During his life Ekmečić was a member of the Serbian Academy of Sciences and Arts from 1978, and a member of its presidency from 2004, and served on five of its specialist committees. He was also a member of the Academy of Sciences and Arts of Bosnia and Herzegovina from 1973, the Montenegrin Academy of Sciences and Arts from 1993, and the Academy of Sciences and Arts of the Republika Srpska from 1996. During his career he received the "27th July Award of Bosnia and Herzegovina for Science" in 1963, the Order of Labour with Golden Wreath in 1965, the "Enlightenment Award" in 1972, and the NIN Award in 1990 for Stvaranje Jugoslavije 1790–1918 , among others. In 2010, the president of the Republika Srpska, Rajko Kuzmanović, decorated Ekmečić with the Order of Honor with Golden Rays. According to an analysis of Serbian historiography after 1991 in the journal Contemporary European History by Christian Axboe Nielsen, an associate professor in the School of Culture and Society at Aarhus University in Denmark, while Ekmečić authored a number of important works in socialist Yugoslavia, he also participated directly as an advisor to the convicted war criminal Radovan Karadžić when he was President of Republika Srpska during the Bosnian War, and was "complicit in the weaponisation of history, in particular that of the mass atrocities of the Second World War". As part of his connection to Karadžić, Ekmečić was also a founder of the radical nationalist Serb Democratic Party in Bosnia and Herzegovina. According to Sabrina P. Ramet, Ekmečić was part of the revisionist wave in Serbian historiography, to which he contributed a religious flavour by claiming that the Catholic Church was the greatest obstacle to the unification of Yugoslavia in 1918, and casting the Vatican as an enemy of the Serbian nation. According to the historian David Bruce MacDonald, Ekmečić was one of many Yugoslav academics that "went national" during the breakup of Yugoslavia, changing his views considerably from his earlier days. Ekmečić died after a short illness at a hospital in Belgrade on 29 August 2015 at the age of 86.
