[1] The county was formed in 1838 and named for Charles Carroll of Carrollton, the last living signer of the Declaration of Independence.

About 10.40% of families and 14.90% of the population were below the poverty line, including 19.80% of those under age 18 and 21.60% of those age 65 or over In 2023, Carroll County Sheriff's Office hired Myles Cosgrove, a police officer who killed Breonna Taylor in 2020 and was subsequently fired by the Louisville Metro Police Department.

The Sheriff's Office said it performed a background check on Cosgrove which he passed.

[11] Carroll County was strongly pro-Confederate during the Civil War: only 2.70 percent of its white population volunteered to serve in the Union Army, which constitutes the fourteenth-lowest of 109 counties extant as of the 1860 election, and was indeed lower than for the whole of seceded Tennessee.

The first Republican to carry Carroll County was Ronald Reagan in 1984, and the growing social liberalism of the Democratic Party has meant the county has voted increasingly Republican since the turn of the century,[14] although Hillary Clinton's 28.69 percent – even if over fifteen percent worse than any previous Democrat – was still as good as she received in any rural white southern county.