Machi (with a single c) is a Sicilian Italian surname, documented by E. Rossoni with its origin in the Palermo area, in western Sicily. Rossoni records it alongside the variant Machì (with a final acute accent) and notes that the original form is probably the accented one, Machì, which suggests an etymology different from that of the northern surname Macchi (with a double c), which is Lombard and derives from the Latin nomen Maccus.

The accented ending in -ì, characteristic of Sicilian onomastics, usually reflects the heritage of Siculo-Greek (suffixes from Byzantine Greek) or of Siculo-Arabic (where the long -i marks the genitive or possession), patterns that were highly productive in the surnames of the Palermo area owing to the history of dominations the island passed through between the 9th and 13th centuries. The distribution of the surname is limited and is concentrated in the Palermo area. The unaccented spelling Machi, frequent in Argentine registers and in modern transcriptions that lose the final graphic sign, is a simplification of the original form Machì.

Despite the similarity with the Lombard surname Macchi, with a double c, Machi has a different origin.