The county was established by the Tennessee General Assembly on October 21, 1823, and is named for U.S.

Weakley County comprises the Martin, TN Micropolitan Statistical Area.

Weakley County was created in October 1823 from some of the land that the Chickasaw people ceded to the United States in the Treaty of 1818.

The county was named after Colonel Robert Weakley, a member of the House of Representatives, a speaker of the State Senate, and the man commissioned to treat (negotiate) with the Chickasaw.

As of the 2020 United States census, there were 32,902 people, 13,640 households, and 8,677 families residing in the county.

27.00% of all households were made up of individuals, and 11.50% had someone living alone who was 65 years of age or older.