Grafenauer started publishing already in the late 1930s.[1] In his academic career, Grafenauer focused on social history in the Middle Ages. He continued the researches of Milko Kos on settlements patterns in the Slovene Lands in the Early Middle Ages, focusing on the Slavic settlement of the Eastern Alps and the medieval Slavic principality of Carantania. He wrote several treatises on the transition between tribal and feudal socio-economic forms in the Eastern Alps and the west Balkans.[1] His main contribution was however the history of the German Peasants' Wars in the late 15th and 16th century in the Slovene Lands and in Croatia. He also wrote on the history of the Slovenes in Carinthia in the 19th and 20th centuries, and on agricultural modernization in the early 19th century. Since the 1950s and 1960s, he was among those who introduced the approaches of the French Annales school in the Yugoslav historiography.
Between 1945 and 1955, he wrote several expert surveys on border areas in Carinthia and the Julian March for the Yugoslav diplomacy.
In the last decade of his life, Grafenauer rose to prominence again with his resolute fight against autochthonist re-interpretations of Slovenian history, especially against the populist Venetic theory, which denied the Slavic settlement in the East Alps.
Bogo Grafenauer died in Ljubljana and was buried in the Žale cemetery. His daughter, Darja Mihelič [sl], is also a historian.