Gemlik is a district and municipality within Bursa Province in Turkey. Covering an area of 401 km2, it has a population of 120,245 as of 2022. The town is situated to the east of the Gulf of Gemlik. In ancient times, Gemlik was the site of the old Greek city of Cius.

Gemlik is an industrial harbor and features a free trade zone center. Significant industrial facilities are present in the southern and western regions of the ports. The Gemlik port ranks among the most active import docks in Turkey. Gemlik is famous for its black olives. The Gulf of Gemlik, 29 km from Bursa has wide sandy beaches; Armutlu and Kumla are the favorites.