Western Armenia is a term to refer to the western parts of the Armenian highlands located within Turkey that comprise the historical homeland of the Armenians. Western Armenia, also referred to as Byzantine Armenia, emerged following the division of Greater Armenia between the Byzantine Empire and Sassanid Persia in AD 387. Since the Armenian genocide, the Armenian diaspora as well as Armenians indigenous to modern Turkey have sought political representation in Western Armenia or reunification with the Republic of Armenia.

The Armenian highlands is the most central and the highest of the three plateaus that together form the northern sector of West Asia. Clockwise starting from the west, the Armenian highlands are bounded by the Anatolian plateau, the Caucasus, the Kura-Aras lowlands, the Iranian Plateau, and Mesopotamia. The highlands are divided into western and eastern regions, defined by the Ararat Valley where Mount Ararat is located. Western Armenia is nowadays referred to as eastern Anatolia, and Eastern Armenia as the Lesser Caucasus or Caucasus Minor, and historically as the Anti-Caucasus, meaning "opposite the Caucasus".