Before the exploration expeditions of the Russian Cossacks in the 17th century, the future Petrovsk-Zabaykalsky's location was a route junction of nomadic Buryat tribes. Peter the Great granted the heads of the tribes with principality. The settlement, founded in 1789 and known then as Petrovsky Zavod (), grew and developed around its iron refinery. From 1830 to 1839, it was a detention place for seventy-one Decembrists and ten of their wives, who were sent here from Chita. There is a commemorating mark on the railway station. In a restored house of the princess Ekaterina Troubetskaya, wife of Sergey Trubetskoy, was organized a museum, which opened on October 10, 1980. In Petrovsk-Zabaykalsky's historical district there are several buildings related to the times of Decembrists in the town.