The capitol's architect was inspired by Classical architecture, and some local newspapers compared the early designs to Greece's Parthenon. Many of the building's details rely on the Corinthian style, in which formality, order, proportion and line are essential design elements. The building is 404 feet (123 m) feet long, 240 feet (73 m) feet wide, and the dome is 250 feet (76 m) high.

The exterior is constructed of Utah granite (Quartz monzonite mined in nearby Little Cottonwood Canyon), as are other Salt Lake City landmarks such as the Salt Lake Temple and LDS Conference Center. The stone facade is symmetrical, with each side being organized around a central pedimented entrance. Fifty-two Corinthian columns, each 32 feet (9.8 m) tall by 3.5 feet (1.1 m) in diameter sitting on an exposed foundation podium, surround around the south (front), east and west sides of the capitol.

The building's interior has five floors (four main floors and a basement). Most of the basement level now contains the base isolators, which are meant to make the building more resistant to earthquakes. The capitol is decorated with many paintings and sculptures of Utah's history and heritage, including statues of Brigham Young, first territorial governor, and Philo T. Farnsworth, Utah native and a developer of television. The floors are made of marble from Georgia.

Beginning in 2004 the capitol experienced a major restoration and renovation project. The project added two new buildings to the capitol complex, while restoring many of the capitol's public spaces to their original appearance. One of the largest projects during the renovation was the addition of a base isolation system which will allow the building to survive as much as a 7.3 magnitude earthquake. After completion of the renovations, the building was rededicated and resumed normal operation in January 2008.