It was founded as a Megarian colony, which soon subjugated the native Mariandynians and extended its power over a considerable territory.

The prosperity of the city, rudely shaken by the Galatians and the Bithynians, was utterly destroyed in the Mithridatic Wars.

[8][9] In the late 19th and early 20th century, Karadeniz Ereğli was part of the Kastamonu Vilayet of the Ottoman Empire.

Ereğli is well developed due to the presence of the steel plant and fishing is a major commercial activity in the city.

[citation needed] Because of its Black Sea beach, Ereğli is a popular tourist destination locally.

[citation needed] The city does not have an airport (Erdemir has a small private field) or rail station, but can be reached by automobile or bus from Ankara, Istanbul and other places.

[citation needed] The discoverer of the northern Turkish coalfields, Uzun Mehmet, lived in the Kestaneci Köyü ("Chestnut-seller Village") section of Ereğli.

[citation needed] The International Love, Peace, Friendship, Culture and Art Festival is held every year in Karadeniz Ereğli.