Unión de Reyes is a municipality and town in the Matanzas Province of Cuba. It is located in the western part of the province, 30 kilometres 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.