Nea Filadelfeia is a suburban town located within the Athens agglomeration in Greece. It serves as the seat of the Nea Filadelfeia-Nea Chalkidona municipality, which is situated in the Central Athens regional unit. The municipal unit covers a total area of 2.850 km².
The town was named after the Anatolian city of Filadelfeia, currently known as Alaşehir in Turkey. It was established by Greek refugees from Asia Minor who relocated to the area following the Greco-Turkish War (1919–1922).