Amadeo was once a barangay of Silang called Masilaw, named after the bright red flowers of the dapdap tree. On July 15, 1872, it became an independent town named after King Amadeo I of Spain. It was briefly merged back with Silang in 1903, but by 1915 it regained its municipal status. Over time, more barangays were created, shaping the Amadeo we know today.