Due to its favorable geographic location, together with excellent natural climatic characteristics, the territory of the present town Kocani was inhabited as early as the ancient times first by the Peonians, Meds and Trachians. Later on in the 6th century the Slavs inhabited parts of the region. More precisely, in the 7th century members of the Slavic tribe Smoljani colonized the Kocani valley and built a fortification. The founders of the Slavic education, brothers Kiril and Metodij lived/stayed in the valley from 845 to 855 and in the Bregalnica area (Morodviz) started to preach Christianity in Slavic language.
Although the settlement existed long before that, the first written document in which the name Kocani is mentioned dated from 1337. Since the end of the 14th century Kocani was under the reign of the Ottoman Empire. According to Evlija Čelebija, Kocani was a little village of 54 christian and 1 muslim families. It's interesting to be mentioned that, in 1660 Kocani had about 3,000 inhabitants with 600 houses, same as Kumanovo. In 1662 the author write in his notes about a settlement with 600 houses and 15 handicraft stores...
In the 16th and 19th century, and especially in the 20th century after the railroad was built in 1926 the town grew considerably.
During the Second World War, Kocani was an important center of the liberation Movement. Aspirations for its liberation never cased to exist. After numerous successful missions the freedom fighters of the 4th Macedonian brigade liberated the town on 7th September 1944. By the happiness didn't last long. Only three days later enemy forces occupied the town again. The final liberation came on 22nd October 1944. The town was left in ashes and ruins. But this didn't discourage the industrious inhibitions. On the ashes of the burned town and centuries-old backwardness, a new life was built. Since the end of Second World War, there has been a great upturn in the region's economic fortunes.