The Belmont County Courthouse is located at 101 West Main Street in St. Clairsville, Ohio. It sits on the highest point in the St. Clairsville area and is thus visible from Interstate 70 and many other points in the Ohio Valley. It is a contributing property in the St. Clairsville Historic District, which was added to the National Register of Historic Places in 1969 .

The three story building is constructed of rusticated sandstone blocks with high arched windows. The building is rectangular with a central projection housing the entrance. The stairs once led to the main entrance, but due to security measures the building is now entered through a tunnel under the stairs. Above the stairs is a false balcony supported by Corinthian columns. A pair of arched windows are flanked by a set of Corinthian pilasters supporting a pediment and a frieze bearing the year "1886" in the center with a fanlight above. The central projection is topped with a pediment with a circle light framed by a carved wreath of flags. Standing guard over the entrance is a statue of Justice.

The rest of the facade on either side of the central projection is symmetrical, with three arched windows on each floor and out-thrust corners. The corner projections contain a single arched window with Doric pilasters on the second floor and Corinthian pilasters on the third. The corners are topped by a pediment with a tower which contains Doric pilasters and arched pediments. The top of each tower is crowned with an urn.

A central tower housing a clock tower and dome rises from the mansard roof. The tower contains high arched windows, Corinthian pilasters, and a small lantern. A steel bell weighing 3,800 pounds once hung from the tower but was taken down during restoration and now rests in front of the courthouse. It rang continuously for an hour in 1945 to celebrate the end of World War II.