Crestonia (Crestonice) was an ancient region immediately north of Mygdonia. The Echidorus river, which flowed through Mygdonia into the Thermaic Gulf, had its source in Crestonia. It was chiefly occupied by a remnant of the Pelasgi, who spoke a different language from their neighbors (Thracians, Paionians; later Macedonians and Hellenes).

The main towns of Crestonia were Creston (Crestone) and "Gallicum " (Romanized name). The region, along with Mygdonia, was held by Paionians for a time, later by Thracians. At the time of the invasion of Xerxes, Crestonia was ruled by an independent Thracian prince (Herodotus, 8. 116). By the time of the commencement of the Peloponnesian war, Crestonia had been annexed to the kingdom of Macedon.

Today, ancient Crestonia is comprehended within the prefectures of Kilkis and part of north Thessaloniki in Greece.