Stevan Petrović was born on 15 February 1807 in Knić near Kragujevac (hence his nickname), during the Serbian Revolution, the region at the time being part of the Sanjak of Smederevo of the Ottoman Empire (today Serbia). During the rule of Prince Miloš Obrenović, Knićanin's political career began as a commissioner of the Jasenica municipality in 1835, and in 1839 as a commissioner of the Smederevo district, but he eventually joined the opposition as a Constitutionalist and supporter of the rival Prince Aleksandar Karađorđević of the Karađorđević dynasty. Since he supported "ustavobranitelji" (the defenders of the constitution), he was expelled from the Principality of Serbia in 1840–1841. He returned in 1842, after Aleksandar Karađorđević had acceded to the throne on 14 September, after being elected the Prince of Serbia at the National Assembly in Vračar.