The Union County Carnegie Library, located at 300 East South Street in Union, South Carolina, is a historic public library and a significant cultural landmark. Commissioned in 1903 and completed in 1905, it holds the distinction of being the first Carnegie library established in South Carolina. Funded by a $10,000 grant from philanthropist Andrew Carnegie, the library was part of his broader initiative to promote public education and literacy through accessible libraries across the United States.

Architecturally, the building is notable for its yellow brick construction accented with red brick and terracotta trim. The facade  features an Ionic portico with a semicircular pediment inscribed with “Carnegie Free Library,” and a low octagonal dome with a finial crowns the roof. In 1968, the interior underwent renovations, but much of the original design and materials were preserved.​

The library is part of the South Street–South Church Street Historic District, which was added to the National Register of Historic Places in 1983. Today, it continues to serve the community as the central branch of the Union County Library System, offering a range of services including book lending, digital resources, and educational programs. Additionally, it supports students and faculty of the University of South Carolina Union campus.