Csepel Island (Hungarian: Csepel-sziget) is the largest island of the River Danube in Hungary. It is 48 km long; its width is 6–8 km. Its area comprises 257 km². The word Csepel is pronounced CHE-pel.
Csepel Island extends south from Budapest; its northern point is Csepel, which is Budapest's District XXI. Most of the island is accessible from Budapest by the suburban railway.