Osmaneli is a town located in the Bilecik Province of Turkey's Marmara region. It serves as the administrative seat of the Osmaneli District.
As of 2021, the town has a population of 16,192. It is bordered by several neighboring areas, including Pamukova to the north, Geyve to the north-east, Gölpazarı to the south-east, Bilecik to the south, Yenişehir to the south-west, and İznik to the west.