Jacksonville is a city in Calhoun County, Alabama, United States. As of the 2020 census the population was 14,385, which is a 14.6% increase since 2010 and a 71.2% increase since 2000. It is included in the Anniston-Oxford Metropolitan Statistical Area. The city is home to Jacksonville State University, which is a center of commerce and one of the largest employers in the area.

Jacksonville was founded in July 20, 1833, on land purchased from Creek Indian Ho-bith Tus-tun-nuck-ie, referred to as "Ladiga" by the men who bought the land. First called Drayton, the town was renamed to honor President Andrew Jackson in 1834. There are several Civil War monuments in town, including a statue of Major John Pelham in the city cemetery and a statue of a Confederate soldier in the middle of the square. Jacksonville served as the county seat for Calhoun County until the 20th century when the county seat moved to Anniston. Jacksonville State University was founded in the city in 1883.

An EF3 tornado hit Jacksonville on March 19, 2018, causing extensive damage to the city and the university of almost $42 million. The relatively low number of casualties – just four injuries – was attributed by some to the fact that the university was on spring break at the time. More than 1,000 volunteers assisted in the immediate tornado relief. Caleb Howard, then a senior at Jacksonville State University, said that "[i]t's been amazing to see the university and the community come together." Classes resumed at the university the following month. Although the university's usual site for graduation, Pete Mathews Coliseum, was damaged in the tornado along with over 20 other buildings, the first spring graduation since the tornado proceeded as scheduled on May 4 outside the football stadium. Dr. John Beeler, the university's president, said "It's a joyous event generally because you're celebrating the accomplishments of all your graduates, but it's an even more joyous event because to me it's a celebration of how far we've come in a short time in recovering from these tornadoes."

Jacksonville is located in the foothills of the Appalachian Mountains. It lies in a valley between Choccolocco Mountain to the east and smaller ridges to the west.

According to the U.S. Census Bureau, the city has a total area of 9.8 square miles (25.5 km²), of which 0.008 square miles (0.02 km²), or 0.10%, is water.

As of the 2020 census, Jacksonville had a population of 14,385. The median age was 24.2 years. 14.9% of residents were under the age of 18 and 12.5% were 65 years of age or older. For every 100 females there were 87.8 males, and for every 100 females age 18 and over there were 86.8 males age 18 and over.

98.1% of residents lived in urban areas, while 1.9% lived in rural areas.

There were 4,823 households and 2,472 families. Of all households, 25.7% had children under the age of 18 living in them. 33.5% were married-couple households, 22.6% were households with a male householder and no spouse or partner present, and 37.6% were households with a female householder and no spouse or partner present. About 35.4% of all households were made up of individuals and 11.5% had someone living alone who was 65 years of age or older.