Gebze (Turkish pronunciation: [ˈɟebze],) is a district in Kocaeli Province, Turkey. It is situated 65 km (30 mi) southeast of Istanbul, on the Gulf of Izmit, the eastern arm of the Sea of Marmara. Gebze is the largest district per population size in the province as of 2020-exceeding İzmit, the provincial capital.
Gebze has experienced rapid growth in recent years, from 159,116 residents in 1990 to 392.945 in 2020.