The western portion of the city, from Gunchū in the north down to Futami's Shimonada in the south, hug the coast of the Inland Sea, nestled in the southwestern section of the Dogo Plain.

[2] Ehime Prefecture Iyo has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light snowfall.

[5] On January 1, 1955, the town of Gunchū was merged with the villages of Kita-yamasaki, Minami-yamasaki and Minami-iyo to form the city of Iyo.

In terms of national politics, the city is part of Ehime 3rd district of the lower house of the Diet of Japan.

[6] Iyo houses the national headquarters for Marutomo and Yamaki, food manufacturing companies that specialize in dried Bonito flakes.