Dezfūl sits on the main north-south highway from Tehrān to Ahvāz, the provincial capital of Khūzestān. The main rail line from Tehrān to the Persian Gulf is 15 km (9 mi) from Dezfūl, on the opposite side of the Dez River.

It is also believed that a fortress protected the strategic bridge across the Dez river, whence the name, although no trace of this castle remains. Interestingly, the old part of the city adjacent to the bridge is known the "Qaleh" (castle). In the middle of the river, close to the bridge you can see remains of several water mills built ca. 300 BC. Most of them were actually used up to the beginning of the 20th century. The last one was in use up to 1985.