The town lies on the Trebišnjica River in Southeastern Herzegovina, some 24km by road from the city of Dubrovnik (Croatia) on the Adriatic Sea. There are several mills along the river, as well as several bridges, including 2 in Trebinje itself, and a historic Ottoman Arslanagic bridge nearby. The river is heavily exploited for hydro-energy. After it passees through the Popovo polje area (South-West of the town), which always floods in winter, it naturally runs underground to the Adriatic Sea, near Dubrovnik in Croatia.

Trebinje on map BiH Population 30,996

There is an Orthodox church in Trebinje, Saborna Crkva, as well as a new monastery, Trebinje Gracanica, located above the town, on the historic hill known as Crkvina, while nearby is also (what is now an Episcopal church) Tvrdoš Monastery, dating back to the 15th century. Trebinje is also home to the Catholic Cathedral of the Birth of Mary. The town largely escaped damage during the war, but Ottoman architecture was destroyed (Resulbegovic Historic House, Sultan's Mosque). The Osman-Pasha (Resulbegovic) Mosque of Trebinje was rebuilt by the returned Bosnian Muslim (Bosniak) community and inaugurated in July 2005. Trebinje is the seat of the Catholic Bishopric of Trebinje-Mrkan. The local football club is FK Leotar Trebinje.