Calumet County was organized in 1836 under the laws of Wisconsin Territory. In 1840, Calumet County's territory was declared to be non-existent and it reverted back to Brown County. It was re-established on February 18, 1842 when the Act declaring Calumet County non-existent was rescinded. The boundaries of Calumet of County were first set in the Revised Statutes of 1849, Chapter 20.

Originally spelled "Chalumet", Calumet County derived its name from a Menominee Indian Village lying on the east shore of Lake Winnebago. The name means 'peace' and signifies the Indian Pipe of Peace. "We Extend the Calumet to All Mankind" was first adopted as the County's official slogan by a county newspaper editor nearly a century. That slogan has remained in use to present day. The Indians believed that the smoke from the Peace Pipes of the resident Menominees ascended to the Great Spirit from within the peaceful border of the County. Traces of prehistoric mound builders can be found today as evidence of their earlier occupation.

Calumet County is truly 'a little piece of heaven'. It is ideally located between Lake Winnebago and Lake Michigan and boasts several parks on the shores of Lake Winnebago. It covers an area of 324 square miles of 207,360 acres. There are nine townships, four incorporated villages and six cities.

The County Seat, originally located in Stockbridge, was moved to Chilton in 1856. The County's population at the time of incorporation was 275. By 1850, it had risen to 1,753. By 1860 census, it had grown to 7,895. Notwithstanding the Civil War, the population continued to grow. In 1870, it had risen to 12,335. Despite poor wheat yields due to disease and drought, the population increased to 16,631 in 1880 where it remained until the early 1960's. Explanations for this lack of growth include the outward migration of the wheat farmers, and the lack of urban centers. The County maintained a farming and manufacturing economy that was heavily reliant upon agriculture. After World War II, people began to migrate from the major city centers and the rural atmosphere became more appealing once more. This trend was a major reason why the population increased from 22,268 to 40,661 residents in 2000.

In 1839, Congress granted the Brothertown Indians rights of citizenship. In 1843, the Stockbridge Indians received similar recognition.

Earliest records available show that the first County Board meeting was held in 1851 in Stockbridge. The first courthouse and jail in the City of Chilton was a wooden structure built in about 1860 at the present site. It was destroyed by fire. The current front portion was rebuilt in 1912. During construction, the courts joined the other county officers located across the street. Once the Courthouse was completed in about January of 1914, the building across the street was used for the County Jail. The first County Board Session held in the new courthouse occurred on January 6, 1914. In 1976, a courthouse/jail addition was constructed to the east and north of the original structure. The second floor was added over the jail portion of the original structure in 1983 for Human Services. The most recent addition occurred in 1998.

The first newspaper was published in 1857, The Chilton Times, John P. Hume, Editor. Colonel Bean established the first bank in 1859 and named it the Shawano Bank of Chilton. The first steam boat to ply the waters of Lake Winnebago was built in Calumet County by the Brothertown Indians under the supervision of Peter Hoteling, a white man and later captain of the boat.