The first documents about Comănești date from 1409, during the reign of Alexandru cel Bun. In an ancient document it is mentioned a village " where there is a Coman", in the District Tazlăul de Sus, as a village of peasants with customs rights upon merchants transiting Trotuș Valley area and for defense purposes. After some research in the archives, the oldest document on the town of Comăneşti would be a letter of June 23, 1606, from  Captain Ioan Matireş to Captain Ion Pettky, stating that the safest route from the Danube to Transylvania is through Comăneşti .

The first cartographic map about Comănești is compiled by geographer Sanson on the Danube map, printed in 1696.

In 1864- through the Law of Local Government Comăneşti Village was established. It  comprised 7 hamlets with 3486 inhabitants. According to the  gazetteer from 1895 five Orthodox churches used to exist in Comăneşti, one Catholic church, two mixed schools, a steam sawmill, more water saws, four springs of mineral water, coal and wax.

An important role in the development of the city, for a century and a half, was played by a strong family called Ghika, that became in the middle of the nineteenth century "Ghika from Comăneşti". Ghika family  land was created between 1800-1804 on the land acquired through various forms or from royal donations. The ambitions of this family, its economic power and the links with other noble families were beneficial for the development of Comănești area. These initiatives resulted in the Comăneşti railway extension and further towards Palanca and the building of Comăneşti Railway Station.

An important event in the life of the village occurred in 1952, by declaring Comănești as a town. Raising the status of Comănești to that of a city took into account its economic strength, the population density and the development prospects of the region. On this occasion the former surrounding villages: Lăloaia, Șupan, Leorda, Lunca de Jos and Șipoteni became quarters of Comăneşti and Vermești and Podei-Podina acquired the quality of localities.

As a size, Comăneşti city is within the IV th category  with a population of 23.924 inhabitants in an area of 6387 ha out of which, 1168.10 in the town and 5218.90 out of the town .