Guźnia [ˈɡuʑɲa] is a village in the administrative district of Gmina Łowicz, within Łowicz County, Łódź Voivodeship, in central Poland. It lies approximately 9 kilometres (6 mi) west of Łowicz and 41 km (25 mi) north-east of the regional capital Łódź. It is located within the historic region of Mazovia.
The village has a population of 175.
Guźnia dates back to the 14th century, and was first mentioned in 1367. Its name is derived from the Old Polish word gozd ("forest"). Guźnia was a private church village within the Polish Crown, administratively located in the Rawa Voivodeship in the Greater Poland Province of the Polish Crown, owned by the Archdiocese of Gniezno.
During the German invasion of Poland, which started World War II, on September 16, 1939, Wehrmacht troops murdered 12 Polish farmers from Guźnia and nearby Bocheń near the Rydwan lake, south Guźnia (see also Nazi crimes against the Polish nation). There is a Polish military cemetery in the village.