Pueblo (/ˈpwɛbloʊ/ PWEB-loh) is a home rule municipality that is the county seat of and the most populous municipality in Pueblo County, Colorado, United States. The city population was 111,876 at the 2020 United States census, making Pueblo the ninth most populous city in Colorado. Pueblo is the principal city of the Pueblo, CO Metropolitan Statistical Area and a major city of the Front Range Urban Corridor.

Pueblo is situated at the confluence of the Arkansas River and Fountain Creek, 112 miles (180 km) south of the Colorado State Capitol in Denver. The area is considered semi-arid desert land, with approximately 12 inches (304.80 mm) of precipitation annually. With its location in the "Banana Belt", Pueblo tends to get less snow than the other major cities in Colorado.

Pueblo is one of the largest steel-producing cities in the United States, for which reason Pueblo is referred to as the "Steel City". The city is also a hub of higher education, enrolling nearly 14,000 students between Colorado State University Pueblo and Pueblo Community College. The Historic Arkansas River Project (HARP) is a riverwalk in the Union Avenue Historic Commercial District, and shows the history of the devastating Pueblo Flood of 1921.

From 1050 to 1450, the area that is now Pueblo was first inhabited by Paleo-Indians and Archaic peoples, as well as people of the Apishapa culture. By 1500, the Ute hunter-gatherers inhabited the region, who hunted in the mountains during the summer and wintered in warmer areas, such as modern-day Pueblo, during the winter. In 1521, Spain assumed control of the land, however, very little settlement or occupation ever occurred. By the time of the 17th century, the Ute acquired horses from the Spanish allowing them to hunt bison on the plains. The Ute bands of the Pueblo area were the Tabaguache and the Muache. Along the eastern Arkansas River, the Jicarilla Apache lived in villages and hunted bison, and grew corn, beans, and squash.

During the middle of the 18th century, the Comanche came through the middle of Colorado on horseback, claiming the Arkansas River valley and pushing up against the boundary of New Spain. The Ute and Comanche formed an alliance, trading and raiding along modern-day Southern Colorado and Northern New Mexico. In 1779 between modern-day Pueblo and Colorado City, Juan Bautista de Anza invaded the area and killed the Comanche leader Cuerno Verde. Despite the loss, the indigenous peoples continued to fight back against the Spanish, with the Comanche claiming swathes of land from Southeastern Colorado to Texas.

By the early 1800's, the Arapaho entered and claimed modern-day Pueblo as well, having a fierce rivalry with the Ute. The area was also frequented by the Cheyenne and the Pawnee.

James Beckwourth, George Simpson, and other trappers such as Mathew Kinkead and John Brown, claimed to have helped construct the plaza that became known as El Pueblo around 1842. According to accounts of residents who traded at the plaza (including that of George Simpson), the Fort Pueblo Massacre happened sometime between December 23 and 25, 1854, by a war party of Utes and Jicarilla Apaches under the leadership of Tierra Blanca, a Ute chief. They allegedly killed between fifteen and nineteen men, as well as captured two children and one woman. The trading post was abandoned after the raid.

In 1848, the United States acquired the Pueblo County area through the Mexican Cession, ending the Mexican-American War. The Colorado Gold Rush began in 1858, springing interest in the area back up. Independence, a traveling camp opened on the east side of Fountain creek, later being named Fountain City once Josiah Smith's prospecting party arrived in September. Pueblo as well as Fountain City were both platted in 1860, with Pueblo later being re-platted in 1870. Pueblo became the namesake of the county when the Colorado Territory was established by Congress in 1861.