The county was named after the castle towns of Viborg (Finnish: Viipuri) and Nyslott (Finnish: Savonlinna, literally New Castle), today located in the towns of Vyborg in Russia and Savonlinna in Finland.

Following the Great Northern War southeastern parts of the county were ceded to Russia in 1721, and the territory that remained was reconstituted into the County of Kymmenegård and Nyslott (Swedish: Kymmenegårds och Nyslotts län, Finnish: Savonlinnan ja Kymenkartanon lääni), with the northern and western parts of County of Kexholm.

After the Russian victory in the Finnish War in 1809, Sweden ceded all its territory in Finland to Russia by the Treaty of Fredrikshamn.

As part of Russian Empire Finland became to constitute a separate grand duchy.

In 1812 Russia made the territories of Vyborg Governorate part of the new Grand Duchy of Finland as Viipuri Province.