The district of Gebze is located in the westernmost portion of Kocaeli Province, with neighbors Tuzla to the west; Pendik, northwest; Sile, north; and Körfez, to the east.

The northern terminus of Osman Gazi Bridge falls within this area; the construction - having a total length of 4 kilometers (with a 1,688-meter main span) - bridges the Sea of Marmara from Kababurun to Dilburnu. The Gebze Metro began construction in 2018 for a 2023 opening. A Marmaray intercontinental commuter rail line connects Gebze to the European side of Istanbul.