Leszno, city, Wielkopolskie województwo (province), west-central Poland. It is a rail junction and an agricultural and manufacturing centre.
Leszno was founded in the 15th century by the prominent Leszczyński family, whose tombs are in the parish church. In the 16th century a band of Protestant Moravian Brothers, expelled from Bohemia, made Leszno a centre of the Reformation. The educator John Amos Comenius lived and taught there. During the 17th and 18th centuries it prospered as a textile and academic centre. It passed to Prussian rule and then returned to Poland after World War I. Pop. (2011) 64,630.