St. Charles is a home rule-class city in Hopkins County, Kentucky, United States.

[3] St. Charles was settled as a coal mining camp in 1872 on land purchased from J.I.D.

In 1873, the post office was established under the name "Woodruff", but when the city was incorporated in 1874, the name was changed to "St. Charles" for now unknown reasons.

The racial makeup of the city was 98.71% White, 0.32% Pacific Islander, and 0.97% from two or more races.

About 26.1% of families and 29.2% of the population were below the poverty line, including 40.6% of those under the age of eighteen and 24.4% of those 65 or over.