Antiquity (6th c. BC – 7th c.)
Thracians settled in the area of today's Aheloy as early as the 6th century BC. Later the site was a small port within the orbit of the Greek colonies of Apollonia (Sozopol) and Mesembria (Nessebar). The name "Aheloy" comes from the Greek "Acheloos" — a river deity meaning "the river".
The Battle of Aheloy (917)
On 20 August 917, on the Anchialus plain — between the fortresses of Anchialo (today's Pomorie) and Mesembria (Nessebar), near the mouth of the River Aheloy — one of the largest battles in medieval Europe was fought. Tsar Simeon I the Great defeated the Byzantine army of Magister Leo Phocas with an enveloping attack from Biberna Hill (near present-day Kableshkovo). Byzantine losses are estimated in the tens of thousands; according to Leo the Deacon, heaps of bones at Anchialo were still visible 75 years after the battle. The victory consolidated Bulgarian supremacy in the Balkans and accelerated recognition of the imperial title of the Bulgarian ruler.
Middle Ages and Ottoman Empire (10th–19th c.)
After the great battle, the site kept strategic significance — a border between the Bulgarian Empire and Byzantium until the 14th century. Under Ottoman rule, Aheloy was a small fishing village with Greek and Bulgarian inhabitants, about 30 houses. In the 19th century, refugees from Eastern Thrace and Asia Minor settled here.
Modern Aheloy (1878 — today)
After the Liberation of 1878, Aheloy remained in Eastern Rumelia, and after the Unification of 6 September 1885 it passed to the united Principality of Bulgaria. In 1967 the village was declared a seaside climatic resort of local importance. On 10 January 2009, by Decree No. 4 of the Council of Ministers (promulgated in State Gazette, issue 6 of 23.01.2009), Aheloy was declared a town — one of the newest settlements with such status in the Burgas region.