Kiernozia [kʲɛrˈnɔʑa] is a town in Łowicz County, Łódź Voivodeship, in central Poland. It is the seat of the gmina (administrative district) called Gmina Kiernozia. It lies approximately 20 kilometres (12 mi) north of Łowicz and 61 km (38 mi) north-east of the regional capital Łódź. It is located in the historic region of Mazovia.

It is the birthplace (and burial place) of Marie Walewska (née Łączyńska), a mistress of Napoleon Bonaparte.