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 Railroad developed a shop and yards in Princeton. This contributed to the growth of the town, which was chartered as a city in 1909.

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. Princeton had an estimated 2012 population of 6,464.