Amite County /ˈeɪ.mɛt/ is a county located in the state of Mississippi on its southern border with Louisiana. As of the 2020 census, the population was 12,720. Its county seat is Liberty. The county is named after the Amite River, which runs through the county. Amite County is part of the McComb, MS micropolitan statistical area.

Amite County was established in February 1809 from the eastern portion of Wilkinson County. It was named after the Amite River. French explorers had named the latter for the friendly (amitié in French) indigenous Houma people they encountered in the region.

The legislation that established the county authorized the appointment of five commissioners to find a site for the county seat, near the county's center and near a good spring; its name was to be Liberty. At this time, the total population of the county numbered about 4000 people, about 80% of whom were middle-class families of seventeenth-century Virginia stock who had gradually migrated through other frontier states. Primary religious groups were all Protestant, including Baptists, Presbyterians, and Methodists.

Completed in 1840, the courthouse in Liberty is the oldest courthouse in Mississippi in continuous use. Liberty eventually became the county's justice and business center. The county economy was based on timber from longleaf pine and the cultivation of commodity crops of cotton, indigo, and tobacco, usually on plantations worked by enslaved African Americans. Given the reliance of planters on labor-intensive crops such as tobacco and cotton, the county soon had a majority population of enslaved African Americans. Even in the antebellum period, the county seat attracted entertainers and lecturers on tour. In the 1850s, Liberty hosted opera singer Jenny Lind, known as the "Swedish Nightingale," at the Walsh building.

In 1861, the state legislature called a convention to vote on secession from the United States. David Hurst, the delegate from Amite County, voted against secession, but the majority of the state's delegates voted for it. Led by South Carolina, the largest slave-owning states were the first in the South to secede. Mississippi voted to join the Confederate States of America. During the Civil War, Captain George H. Tichenor married Margaret Anne Drane at the Liberty Baptist Church; Tichenor developed an antiseptic to treat wounds suffered by soldiers in the war. By the end of the war, 279 men from Amite County had died for the Confederate cause. Amite County was not in a theater of war.

A raiding party of Union cavalry, under the command of Colonel Benjamin Grierson, is known to have camped in the county nine miles east of Liberty on the evening of April 28, 1863, while conducting a deep penetration raid as part of the Vicksburg Campaign. As part of that raid, Union forces pillaged many homes and plantations. Most of the buildings of the Amite Female Seminary, with 13 pianos, were burnt; one building was spared, the small Mary Van Norman Ratcliff Building, commonly known as the "Little Red Schoolhouse."

At the end of the Civil War, Amite County's population was 60% African American. During Reconstruction, freedmen elected several African Americans to local office as county sheriff. After Reconstruction, white Democrats regained power in the state legislature through a combination of violent voter repression and fraud. They disenfranchised most African Americans and many poor whites in the state by the new 1890 state constitution, which imposed a poll tax, literacy tests, and other requirements as barriers to voter registration. These were administered by whites in a discriminatory way. Most black voters and many poor whites were dropped from the voter rolls.

Racial violence, including lynchings, escalated during the Jim Crow years. The county had 14 documented lynchings in the period from 1877 to 1950; most took place around the turn of the century when disenfranchisement and imposition of Jim Crow was underway.