Pratt County is a county located in the U.S. state of Kansas. Its county seat and largest city is Pratt. As of the 2020 census, the county population was 9,157. The county was named for Caleb Pratt, a U.S. soldier who died in the Battle of Wilson's Creek during the Civil War and who had previously been involved in Bleeding Kansas.

The county consists overwhelmingly of prairie and contains few watercourses; the most important of these is the Ninnescah River.

Farming continues to be important to the county, which is among the state’s leading winter wheat producers.

Pratt County was established in 1867. The county's first attempt at organization, termed the "fraudulent organization," occurred in 1873. A group from Hutchinson traveled through various counties, organizing them as they went. However, since there were no genuine settlers in Pratt County at the time, this organization required the submission of false statements to the governor. This fraudulent attempt was not recognized, and the Pratt County was legitimately organized in 1879.

The county's first bona fide settler, A. J. Johnson, arrived in the fall of 1873 near Springvale in the southwest corner, where he cultivated the county's first crops. The county saw significant settlement in 1877, primarily from Iowa, and further in 1878 from all sections of the United States, keeping land office officials busy with pre-emption claims. Despite a prosperous period for crops in 1879 and 1880, many settlers departed in subsequent years, while others arrived in large numbers, especially in 1882. During the county's early years, owing to the scarcity of lumber, many constructed sod houses or dugouts.

The special election of September 2, 1879, focused on the choice of a county seat, was disputed due to irregularities. After a lawsuit second election was scheduled for August 19, 1880. In the lead-up to that election, a proponent of Saratoga named W. F. Gibbons made a deal with W. H. Weidner from Medicine Lodge, agreeing to pay him $40 to bring about fifteen cowboys into Pratt County thirty days before the election to vote for Saratoga. Each cowboy was promised $5, free whisky, and a free dance at Saratoga on the night of the election. Weidner located the cowboys and provided Gibbons with a list of names as agreed, receiving $25 as part payment. However, due to a contract dispute, all the cowboys left Pratt County before the election, causing Saratoga to lose their intended votes. Iuka was ultimately declared the county seat with a significant majority.

Efforts to relocate the county seat to Pratt commenced in 1885 and succeeded in 1888 over the objections of Saratoga. An 1888 blizzard killed over 80% of the county's cattle, causing widespread hardship.

In 1887, the Chicago, Kansas and Nebraska Railway extended its main line from Herington to Pratt. This main line connected Herington, Ramona, Tampa, Durham, Waldeck, Canton, Galva, McPherson, Groveland, Inman, Medora, Hutchinson, Whiteside, Partridge, Arlington, Langdon, Turon, Preston, Natrona and Pratt. In 1888, this main line was extended to Liberal. Later, this line was extended to Tucumcari, New Mexico and El Paso, Texas. This line is called the "Golden State Limited".