San Emilio, officially the Municipality of San Emilio (; ), is a municipality in the province of Ilocos Sur, Philippines. According to the , it has a population of people.
San Emilio is situated from the provincial capital Vigan, and from the country's capital city of Manila.
San Emilio is politically subdivided into 8 barangays. Each barangay consists of puroks and some have sitios.
In the 2024 census, San Emilio had a population of 7,513 people. The population density was .
San Emilio is part of the second congressional district of the province of Ilocos Sur. It is governed by a mayor, designated as its local chief executive, and by a municipal council as its legislative body in accordance with the Local Government Code. The mayor, vice mayor, and the councilors are elected directly by the people through an election which is being held every three years.
The Banayoyo-Lidlidda-San Emilio Schools District Office governs all public and private education systems. Its jurisdiction includes the Municipality of San Emilio, including the towns of Banayoyo, and Lidlidda.