Tuao, officially the Municipality of Tuao (Ibanag: Ili nat Tuao; Ilocano: Ili ti Tuao; Tagalog: Bayan ng Tuao), is a municipality in the province of Cagayan, Philippines. According to the 2024 census, it has a population of 66,147 people.

When the early Spanish missionaries were busy laying the foundation of a church late in the 16th century at a site about six kilometers from the present town of Tuao, a big bird came circling over them and then alighted on the wooden cross erected to mark the place where the cornerstone was laid. It flapped its wings noisily, onomatopoetically sounding like "battuao, battuao, battuao" and then flew away.

When the civil authorities founded the town in 1604, the natives insisted that it be called Tuao. Eight years later on May 13, 1612, Tuao was accepted ecclesiastically. Father Miguel de San Jacinto, O.P. gave the town Santos Angeles Custudios (Holy Guardian Angels) as its patron saints.

The early missionaries in Tuao were zealous evangelists and tactful pacifiers of warlike natives. One of them was Father Francisco Capillas, who later became the first martyr in China. The first parish priest, Father Juan B. Cano, O.P. worked patiently with the people. Another missionary, Father Gabriel Serrano, O.P. built a strong brick and mortar church, a rectory (convento) and a fort (cotta) in which the Spaniards and the natives sought refuge every time the town was raided by the Kalingas from the Cordillera ranges. These landmarks were destroyed by a strong earthquake on December 29, 1949.

In protest of abuses committed by Spanish civil officials and soldiers, the inhabitants of Tuao and neighboring Malaueg, rose in revolt in 1718 under Luis Magtangaga and Tomas Sinaguingan. The uprising was put down by Capitan Juan Pablo de Orduna.

During World War II, Tuao was the seat of the provincial resistance government of Governor Marcelo Adduru. The Japanese Forces garrisoned the town when Adduru was captured late in 1943, but Adduru returned shortly after having been freed by the guerillas early in 1944. Donald Blackburn, "assisted by his intelligence officer Lt. Mariano D. Manawis, from the prominent Daquial family who served in the 11th Infantry;"; staged from Tuao, his guerrilla headquarters, attacks against the Japanese in Tuguegarao.

Tuao is situated 42.35 kilometres (26.32 mi) from the provincial capital Tuguegarao, and 510.24 kilometres (317.05 mi) from the country's capital city of Manila.

Tuao is politically subdivided into 32 barangays. Each barangay consists of puroks while some have sitios.