Miroslav Brandt was born at Cerić near Vinkovci in eastern Croatia on 2 March 1914. His family already left in the following year and resettled in Zagreb, where Brandt attended elementary school and completed the real gymnasium in 1932. He initially studied medicine, but then dedicated himself to the study of world and national history, geography and Latin at the end of the Second World War. In 1948, he was hired as a curator of the Historical Museum of Croatia. He became a librarian in the National and University Library in Zagreb in the next year, and then he became an assistant in the History Institute at the Yugoslav Academy of Science and Arts in 1950. Two years later, Brandt began lecturing on medieval world history at the Faculty of the Humanities in Zagreb. He departed for the College de France and Archives Nationales in Paris in the same year. After working at the archives in Zagreb, Paris, London and Oxford, he earned his Ph.D. with a dissertation on the economic-social history of medieval Split. Later, he also wrote about the heresy of John Wycliffe and social movements in Split at the end of the 14^th century.

The first phase of Brandt's involvement in historiography and his public work clearly demonstrated his Marxist orientation. In the second phase in the 1970s and 1980s, he moved away from a such an approach in his most important work, Srednjovjekovno doba povijesnog razvitka  (The Medieval Era of Historical Development) in 1980, in which he offered a synthesis of the general history of the medieval period from different research angles, and in his studies of Russian medieval history and the history of heretical movements, with less emphasis on its social dimension, and more on an analysis of the theological and philosophical character of Gnostic/dualist beliefs. The change in political attitudes left a mark in his historiographic work. Brandt explained that his orientation toward world themes in medieval history was due to the fact that he could not deal with medieval Croatian history because of political concerns. His other colleagues were willing to write in the political line with the Communist Party, about which he wrote in his autobiographical work under the title Život sa suvremenicima (Life with My Contemporaries). Brandt's subjective stance was that work could serve as a historical source for researching relationships in socialist Croatia between the regime and the “dishonest” intelligentsia, to which he had alluded. However, the breadth of Brandt's interests was not limited to the sphere of historiography, for he was also interested in literature and translation, so that he translated some German and French books on history and literature. He was the translator of some historiographic classics in Croatian, such as the work of well-known Belgian historian Henri Pirrene A History of Europe: From the End of the Roman World in the West to the Beginnings of the Western States, and also the book of French historian Marc Bloch Feudal Society and the novels of Marcel Proust, such as  Combray and Swann’s Way.

Brandt was a professor of medieval world history at the Faculty of Humanities at the University of Zagreb from 1957 to 1984. His period of dissent began when he was vice president of Matica Hrvatska  from 1963 to 1971. Brandt entered the heart of events during the national movement in the 1960s when he made a significant contribution to the writing and composition the text of the Declaration on the Name and Status of Croatian Language in 1967. After the fall of Croatian Spring in 1971, Brandt was practically removed from public and cultural life due to his dissent against the regime. In the same period, he began to suffer from the consequences of a heart-attack which he endured as a result of the atmosphere of persecution and intimidation by the regime against the Croatian intelligentsia of the Croatian Spring (1967-1971). Thereafter, Brandt appeared to forsake the socialist ideology in his manuscripts since 1971, and in a particular the Yugoslav version of socialism and its solution to the national question. At the end of 1989, Brandt returned to public life when he insisted on organizing Matica Hrvatska again, whose work was prohibited by the regime since 1971. In the meantime, Brandt secretly wrote a critical response to the Memorandum of the Serbian Academy of Science and Arts in 1986 in which he opposed the Serbian policy of securing Serbia’s predominance in the Yugoslav federation after Tito's death. The final epilogue of his criticism of communist ideology was his last work, Triptych, an historical-polemical book which was published in 1992. He died in Zagreb on 21 July 2002 at the age of 88.