Mariachi (US: , UK: , Spanish: [maˈɾjatʃi]) is a genre of regional Mexican music that dates back to at least the 18th century, evolving over time in the countryside of various regions of western Mexico. The usual mariachi group today consists of as many as eight violins, two trumpets and at least one guitar, including a high-pitched vihuela and an acoustic bass guitar called a guitarrón, and all players taking turns singing lead and doing backup vocals.

From the 19th to 20th century, migrations from rural areas into Guadalajara, along with the Mexican government's cultural promotion gradually re-labeled it as son style, with its alternative name of mariachi becoming used for the 'urban' form. Modifications of the music include influences from other music such as polkas and waltzes, the addition of trumpets and the use of charro outfits by mariachi musicians. The musical style began to take on national prominence in the first half of the 20th century, with its promotion at presidential inaugurations and on the radio in the 1920s. In 2011, UNESCO recognized mariachi as an Intangible Cultural Heritage, joining six other entries on the Mexican list of that category.

Song styles and instrumentals performed with mariachi include rancheras, corridos, cumbias, boleros, ballads, sones, huapangos, jarabes, danzones, joropos, pasodobles, marches, polkas, waltzes and chotís. Most song lyrics are about machismo, love, betrayal, death, politics, revolutionary heroes and country life.