During the Middle Ages it was a Bulgarian fortress of importance during Tsar Samuil's wars (r. 997–1014) with Byzantium.

During Ottoman rule, it formed part of the Rumeli Eyalet, and in the 19th century became a kaza of the Sanjak of Serres in the Salonica Vilayet.

According to local historians, the present-day town of Petrich is the heir to the ancient Thracian settlement located at the southern foot of the Kozhuh hill.

In this area, located 10 km northeast of the modern city, in the 4th century BC, a Thracian settlement of the Medi tribe emerged.

Recent archaeological research and the location of the ancient city of Heraclea Sintica in the Kozhuh area prove that there is no continuity between this city, located in the lands of the Thracian Sinti tribe, and modern Petrich, but a hiatus of several centuries.

Petrich was formed as a significant settlement and regional center only at the end of the XII - XIV century.

At the end of the 10th and the beginning of the 11th century, the lands around Petrich occupied an important military-strategic place in Samuel's state.

During the period XII - XIV century Petrich became a strong fortress - part of the fortification system in southwestern Bulgaria.

The town fell under Ottoman rule after 1395, when together with its surroundings it was included in the Kyustendil Sanjak as a center of independent Nahiyah.

The Ottoman traveler Evliya Çelebi visited Petrich in 1652 and reported that the palanquin had 240 not very well-developed houses with gardens.

[7] By virtue of the San Stefano Peace Treaty of 1878, the city entered the borders of liberated Bulgaria.

The town experiences some continental influence, especially in winter, which is cool, but warm for Bulgarian standards.

Petrich is the sunniest city in Bulgaria slightly ahead of Sandanski with yearly sunshine hours exceeding 2,700 on average.

Summer is hot and sunny and it is the longest season in Petrich, lasting from May through September, even as late as October.