İzmir Province (Turkish: Izmir ili) is a province and metropolitan municipality of Turkey in western Anatolia, situated along the Aegean coast. Its capital is the city of İzmir, which is in itself composed of the province's central 10 districts out of 30 in total. To the west, it is surrounded by the Aegean Sea, and it encloses the Gulf of Izmir. Its area is 11,973 square kilometres (4,623 square miles), with a population of 4,279,677 in 2017. The population was 3,370,866 in 2000. Neighboring provinces are Balıkesir to the north, Manisa to the east, and Aydın to the south. The traffic code of the province is 35.
Major rivers of the province include the Küçük Menderes river, Koca Çay (with Güzelhisar dam), and Bakırçay.