Karacabey is a municipality and district of Bursa Province, Turkey.

The district of Karacabey borders the districts of Mudanya and Nilüfer from east, Mustafakemalpaşa and Susurluk from south, Manyas from southwest and Bandırma from west.

It is known as the plantation area of a special variety of onions.

Miletopolis was apparently the chief settlement of a group of people called the Milatæ, whose name was hellenized to suggest a Milesian colony.

Around the end of the twelfth century, it was united with Lopadium as an archbishopric.