Unión de Reyes is a municipality and town in the Matanzas Province of Cuba. It is located in the western part of the province, south of Matanzas, the provincial capital.
Unión de Reyes was founded in 1844, and it was established as a municipality on July 1, 1879. Its name derives from Unión en el Punto de Reyes, so named for its location at a railway junction.
The municipality, originally divided into the barrios of Iglesia and Unión, is divided into 9 consejos populares (i.e. "people's councils"): the town of Unión de Reyes and the villages of Alacranes, Bermejas, Cabezas, Cidra, Estante, Juan ÃÂvila, Juan G. Gómez and Puerto Rico.
In 2022, the municipality of Unión de Reyes had a population of 35,021. With a total area of , it has a population density of .