The Vilayet of Sivas (Armenian: Սեբաստիայի նահանգ, Ottoman Turkish: ولايت سيوس, romanized: Vilâyet-i Sivas) was a first-level administrative division (vilayet) of the Ottoman Empire, and was one of the Six Armenian vilayets. The vilayet was bordered by Erzurum Vilayet to the east, Mamuretülaziz Vilayet to the south-east, the Trebizond Vilayet to the north and Ankara Vilayet to the west.
At the beginning of the 20th century, it had an area of 32,308 square miles (83,680 km), while the preliminary results of the first Ottoman census of 1885 (published in 1908) gave the population as 996,126. The accuracy of the population figures ranges from "approximate" to "merely conjectural" depending on the region from which they were gathered.