Following a research tour of Italy and Greece, Busolt habilitated in 1878 at Königsberg with his work on Sparta.
His first chair received Busolt in 1879: He followed Christian August Volquardsen as Professor of Ancient History at the University of Kiel.
After 18 years in Kiel Busolt changed for the winter semester 1897/98 at the University of Göttingen, where he again succeeded Volquardsen.
To this end, he wrote a handbook on the ancient Greek city and his multi-volume Griechische Geschichte.
Although he intended to cover the subject down to the Battle of Chaeroneia, Busolt's work goes only as far as the Peloponnesian War.