Eskilstuna's history dates back to medieval times when English monk Saint Eskil made "Tuna" his base and diocese of the South coast of Lake Mälaren.

Saint Eskil was stoned to death by the pagan vikings of neighbouring town Strängnäs, 30 kilometres (19 miles) east of Eskilstuna, when he tried to convert them to Christianity.

The monastery of Saint Eskil was completely destroyed by Swedish king Gustav Vasa during the Protestant Reformation and was replaced with the royal castle of Eskilstuna House.

Later the pagan city of Strängnäs was Christianised and was given the privilege of becoming diocese of South Lake Mälaren, and "Eskil" was combined with "Tuna", although the town of Eskilstuna did not receive municipal privileges due to its proximity to the medieval city of Torshälla.

Aside from firearms, the city also produced superior carpentry and wood carving chisels, cutlery, scissors, keys, machine tools and precision instruments.

Eskilstuna remains an important industrial city with internationally known companies such as Volvo Wheel loaders, main site for the heavy construction equipment division of Volvo, Assa (locks, keys), and Stainless steel manufacturer Outokumpu, Thin Strip Nyby in Torshälla.

Unlike the coastal part of the Sörmlandic region, Eskilstuna has higher diurnal temperature variation and stronger waves of either heat or cold.

With regards to daytime maximum and minimum temperatures, the weather station has been operated since 1961 with a total of three breaks of 2-3 years apiece in between 1984 and 2008.

The stadium Tunavallen was a venue for the 1958 FIFA World Cup, hosting one match between Paraguay and Yugoslavia.