Princeton, the county seat of Mercer County, was named for the Battle of Princeton in New Jersey, where the county's namesake, Revolutionary Gen. Hugh Mercer, had died. When the county was formed in 1837, William Smith donated 1.5 acres of land for a courthouse. The post office was opened in 1838. By 1860, Princeton had grown to about 40 houses and two hotels. During the Civil War, the town was briefly occupied by the Confederates under Col. Walter Jenifer. When Jenifer was forced to evacuate the town, he ordered it burned. Only a few structures escaped destruction.

Fortunately, county records had been removed to Concord Church, now Athens, and were later returned to Princeton. There were unsuccessful attempts to move the county seat to Concord Church or to Bluefield. Following the Civil War, Princeton grew, a bank was established there, and the town became a trading center. In 1905, the Virginian Railway developed a shop and yards in Princeton. This contributed to the growth of the town, which was chartered as a city in 1909. Princeton’s population more than doubled, from 3,027 to 6,224, between 1910 and 1920. That growth continued until the population peaked at 8,393 in 1960. In 2020, the population was 5,872, an 8.7 percent decline since the 2010 census. As of 2020, it was West Virginia’s 23rd largest city.

Two major highways, Interstate 77 and U.S. 460, intersect outside Princeton and have contributed to its recent growth with the construction of motels and restaurants. Princeton is the southern terminus of the West Virginia Turnpike, which coincides with I-77 from there to Charleston. Several industries have also located in the city. Princeton had a small airport, which was used for flight training during World War II. The former airport is now the location of the city hall, a softball field, and Princeton Community Hospital. Recreational facilities include a minor league baseball team as well as a city park.