Researchers have attempted to link the village's name to that of Rhesus of Thrace, a Thracian king of the Iliad, and although the existence of an ancient settlement at the place of the modern village has been proven (with the oldest artifacts dating to the 4th century BC), it is hard to establish any connection with Rhesus' personality. In ancient times, the area was subject to large-scale metallurgical activity, with the largest ancient deposit of slagin Bulgaria. It is believed that the medieval fortress of Castrition lay on Cape Kastrich north of modern Rezovo.
Today's village was first mentioned in Ottoman registers as Rezvi, a village of 41 Christian families. In the 18th century, it was noted as B�y�k Rezve ("Big Rezve") and marked as a sea port on Ottoman maps. According to Austrian Wenzel von Bronjar and other 18th-century western travellers, the river mouth at that place had a goodwharf suitable as a storm and winter shelter. Rezovo has changed its location slightly several times: its oldest known location is the same as today's, at the coast. However, the locals were forced to move inland because of persistent raids by Caucasian Laz pirates, settling during the 19th century in the Kladarsko Bardo area 10 kilometres to the west, also along the Rezovo River. By 1900, that "Old Rezovo" had 70�80 houses and anEastern Orthodox church of Saint Elijah the Forerunner. The seaside land was not completely abandoned, as it was used as a pasture because of the favourable climate.
In 1903, the residents of Rezovo took an active part in the Bulgarian Ilinden-Preobrazhenie Uprising, seeking unification with their compatriots in the Principality of Bulgaria. However, the revolt was crushed by the Ottoman authorities and most of Old Rezovo was burned to the ground. The surviving locals settled on the coast, approximately where the oldest known incarnation of the village had been. The Church of Saints Constantine and Helena was built in 1906. After the Balkan
