Hennef (Sieg) (German pronunciation: [ˈhɛnɛf] ⓘ) is a town in the Rhein-Sieg district of North Rhine-Westphalia, Germany.

It is situated on the river Sieg, approx.

7 kilometres (4 miles) south-east of Siegburg and 15 km (9 mi) east of Bonn.

Hennef is the fourth-biggest town in the Rhein-Sieg-Kreis (i.e.

Hennef is known as the "City of 100 villages".