From 1958 he dedicated himself to historiography and started his academic career as a researcher at the History Department of the Institute of Social Sciences (May 1958-August 1963).

His academic archives, found after his death, were source for additional six books (out of which one was published in the United States) and ten new scientific papers.

Historian Ljubodrag Dimić, in his Foreword to Branko Petranović: The Yugoslav Experience of Serbian National Integration, stressed that the twentieth century epoch in Yugoslavia was not inclined to the historian, especially not to the one who was trying to gain rational knowledge about the history of the Yugoslav state and society.

In the first years following the Second World War, ideological and political conditions were not favorable for the study of history.

He stated that the dictatorships weren't able to counter taboos, religious intolerance and divisions, the uneven economic development of Yugoslav regions, and the influence and interest of great powers.

[4] His overall research can be summarized by the twentieth century themes[6] Petranović influenced a group of his students who became later historians at Belgrade University: Ljubodrag Dimić, Desanka Pešić, Latinka Perović, for example.