Miączyn [ˈmjɔnt͡ʂɨn] is a village in the administrative district of Gmina Czerwińsk nad Wisłą, within Płońsk County, Masovian Voivodeship, in east-central Poland. It lies approximately 10 kilometres (6 mi) east of Czerwińsk nad Wisłą, 25 km (16 mi) south of Płońsk, and 45 km (28 mi) north-west of Warsaw.