Joniec [ˈjɔɲɛt͡s] is a village in Płońsk County, Masovian Voivodeship, in east-central Poland. It is the seat of the gmina (administrative district) called Gmina Joniec. It lies approximately 15 kilometres (9 mi) east of Płońsk and 52 km (32 mi) north-west of Warsaw.