Fellin County was an administrative unit of the Livonia Governorate of the Russian Empire, later of Estonia, which existed from 1745 to 1920. Its center was the town of Fellin.
The county was formed in 1745 as part of the Riga Governorate. In 1796, after the transformation of the Riga Viceroyalty, Fellin County became part of the Livonia Governorate. In 1920, the county passed to the independent Republic of Estonia.
