The urban center is constituted by two former villages (Canneto and Montrone) that were separated for a long time. Canneto was founded by the Normans of Robert Guiscard between 1080 and 1090, on the place of an ancient center (probably to be identified with Celiae), documented from ceramics and more recent graves from the 4th century. Montrone was founded in 980 by Greek refugees. Both had been subdued to varied feudal lords until 1806, when feudalism was abolished in the Kingdom of Two Sicilies. The two centers were united in 1927 under the artificial name of Adelfia, from the Greek term adelphòs, meaning brotherhood.
Between the 19th and the 20th century they suffered a considerable emigration towards the United States. The city life is today mainly connected to that of the nearby Bari.