[2] The county was created in 1818[3] and is named for Major General Jacob Brown, an officer in the War of 1812 who was wounded at the Battle of Lundy's Lane.

[4] Brown County is part of the Cincinnati-Middletown, OH-KY-IN Metropolitan Statistical Area.

After the American Revolutionary War, the federal government established the Northwest Territory, a large area which encompassed the present county.

This lasted for two decades, during which the area north of the Ohio River attracted settlers.

Among the early settlers was Jesse Root Grant (father of future US President Grant), who built a home and set up a tannery in the future Georgetown area, where young Hiram Ulysses (later changed to Ulysses S.) spent his youth.

[3] Brown County was said to be the place of origin of the White Burley type of tobacco, grown in 1864 by George Webb and Joseph Fore on the farm of Captain Frederick Kautz near Higginsport, with seed from Bracken County, Kentucky.

By 1883, the principal market for this tobacco was Cincinnati, but it was grown throughout central Kentucky and Middle Tennessee.

Brown County lies on the south line of the state of Ohio.

White Oak Creek flows southward through the lower part of southwest Brown County, discharging into the Ohio at Higginsport; Straight Creek flows southwestward through the lower central part of the county, discharging into the Ohio two miles (3.2 km) east of Higginsport.

Eagle Creek flows southerly through the lower eastern part of the county, discharging into the Ohio east of Ripley.

The terrain of Brown County consists of low rolling hills, carved by drainages.

Prior to 1928, Brown County was a Democratic Party stronghold in presidential elections.