The first recorded document mentioning Debar is the map of Ptolemy, dating around the middle of the 2nd century, in which it is called Deborus. The Byzantine emperor Basil 2nd knew of its existence, and Felix Petancic referred to it as Dibri in 1502 (this was during the period of the Ottoman empire).
The town was subsequently conquered by the 1st Bulgarian Empire, later by the Samoil's empire, but lost to the Byzantines under Tsar Samoil by the early 11th century, as his empire was subjugated. In the 11th century, according to the documents of Vasilius 2nd, Debar belonged to the bishopric of the Bishop of Bitola.
Bohemond and his Norman army took the city in 1107. In the 13th-14th century, Debar changed hands between Despotate of Epirus, the 2nd Bulgarian Empire, Byzantine Empire and Serbia.
During the time of the prince Gjergj Kastriot Skenderbeg (Gjorgi Kastriot), Debar played a major role in the rebellions of Albanian population against the Ottomans. Debar region was the borderline between the Ottomans and the rebels between 1443 and 1465 and became an area of continuous conflict. There were two major battles near Debar April 29th, 1444 and September 27th, 1446, both ending as Ottoman defeats. In 1449, Debar fell under Turkish power and was named Dibri/Debra. In the 15th century, Debar was known for being the town of rebellions against the Turkish sultan, but at the same time, for the wealth of the numerous Turkish Aga and Bey who used to live there.
In the early 19th century, when Debar rebelled against the Turkish Sultan, the French traveller, publicist, and scientist Ami Bue observed that Debar had 64 shops and 4,200 residents.
During 19th century, Debar is known for its rebellions against the Turkish Sultan. In the 19th century, the traveler Ami Bue has observed that Debar had 64 shops and 4,200 residents. Debar was significantly involved in the national Albanian movement and on November 1st 1878 the Albanian leaders of the city participated in founding the League of Prizren.
During the Balkan Wars (1912-1913), the town was annexed by the Kingdom of Serbia. In September 1913 there was uprising in Debar against remaining in Kingdom of Yugoslavia. In September of 1913 during an Albanian invasion of Serbia, Albanian armed forces occupied the city, but the Serbian Army regained it later that month.
By the end of the century, Debar had 15,500 residents, but after the First World War, this number started to decline.