The first settlements uncovered by archeologists in Alimos date back to the Neolithic period, and the excavation site can be found in the region of Euonymeia (Ano Kalamaki), immediately by the Vouliagmenis Avenue.
In classical antiquity, Halimous (Ancient Greek: Ἁλιμοῦς; also Alimous, Ἀλιμοῦς) was a fishing town on the outskirts of the city-state of Athens and constituted one of the demes of Attica. The area of Ano Kalamaki, known as Euonymeia, constituted a distinct settlement, which in classical antiquity became the urban (Asty) Deme of Euonymos. Testament to its development during this period are the ruins of the amphitheater of Euonymos, quite unusual in the ancient world in its rectangular design. The site can be found on Archaiou Theatrou Street in Ano Kalamaki (just a few blocks away from the Neolithic site).
The most significant historical affiliation of Alimos is that with Thucydides. Thucydides was born in Halimous, and is often referred to as "Thucydides the Halimousian" (Greek: Θουκυδίδης ο Αλιμούσιος). The bust of Thucydides is the emblem of Alimos, which is commonly used between schools in the area. Furthermore, the First High School of Alimos is called Thoukydidio (Greek: Θουκυδίδειο), after him.
Kalamaki was part of the community of Brachami until 1927, when it became a separate community. The community Kalamaki was abolished in 1968, when the municipality Alimos was founded.