The first population centers of Amêndoa date back to pre-historic times, and from this time some vestiges were found, such as the Cabeço das Penedentas dolmen in the village of Pêro Gonçalves, where a slate plate with two holes at the top representing an idol, very common in Lusitania and exclusive to the Iberian Peninsula, was found. Another great historical landmark was the discovery of the Castro de São Miguel, in Serra da Ladeira. In its surroundings was collected a large collection of objects such as millstones, axes, spears, alvions, engraved copper plates, and ceramics. This Celtic settlement still has the remains of a wall that dates back to 350 B.C..
The Romans called this land Amindula, which was situated on the edge of the Roman road that went from Egitânia to Abrantes. In a place called Coutada, some fragments of polychrome "opustelatum", parts of Roman mosaic with geometric decoration and ceramics from the 1st century BC were collected.
After the reconquest from the Moors by D. Afonso Henriques in 1165, Amêndoa was donated to the Templars, to whom it belonged until 1174. In 1231, it already belonged to the Order of Saint John of Jerusalem, later of Rhodes, which had been given all the land of Guidintesta by D. Sancho I in 1194, being already a very autonomous population in 1336 as it had judges, almotacés, and all the jurisdiction proper of a village, even receiving all the rents and royal rights. In 1372, D. Fernando I donated to D. Afonso Fernandes de Lacerda, among other things, half the village with all the jurisdictions, which later came to fall on the Lords of Belas and Lords and then Counts of Pombeiro.
In the year 1514 by order of D. Manuel I it became a commendation of the Order of Christ, and in 1527 D. João III ordered the first "General Census of the Population". At that date Amêndoa registered 36 fires and 162 inhabitants, and the town was later to become the Lordship of the Counts of Abrantes and, by succession, of the Counts of Penaguião and Marquises of Fontes, after Abrantes.
After six hundred years as a county, in 1836, Amêndoa was downgraded to the category of parish, being integrated in the county of Vila de Rei until 1878, when it became part of the county of Mação.