The Archdiocese of Gniezno is the oldest Latin Catholic archdiocese in Poland, located in the city of Gniezno. The ecclesiastical province comprises the suffragan dioceses of Bydgoszcz and Włocławek.

Gniezno is a city in central-western Poland, about 50 kilometres east of Poznań. Its population in 2021 was 66,769, making it the sixth-largest city in the Greater Poland Voivodeship. One of the Piast dynasty's chief cities, it was the first historical capital of Poland in the 10th century and early 11th century, and it was mentioned in 10th-century sources, possibly including the Dagome Iudex, as the capital of Piast Poland.