This impressive Romanesque Revival structure rules over Welch's compact downtown from a grassy throne high above Wyoming Street. The core structure is a very early work of the important Southern architect Frank Pierce Milburn (1868–1926), who was twenty-five years old when his design was selected in a competition that received input from twelve architects. As first built, the courthouse took the shape of a cross with shallow arms, some 90-by-56 feet in overall dimensions. A single-bay entrance pavilion advances slightly from the center of the west facade, and a tall tower, its large arches filled with handsome metal filigree and louvers, rises at the northwest corner. All exterior walls are of quarry-faced Berea (Ohio) sandstone, laid in alternating wide and narrow courses, the latter appearing almost as mortar joints. Inside, the cast iron stairway to the second-floor courtroom is the most impressive original feature.

The Bluefield firm of W. E. and E. L. Shufflebarger designed the 1908–1909 northern addition, which replaced Milburn's sheriff's residence. It is connected to the original structure only at the second-floor level, by a short “bridge” supported by columns. In scale, design, and materials, the annex carefully respects the character of the earlier building. Later, more modest additions have been made both south (1963) and north (1979). These also show careful attention to material and scale.

As the center of a county whose entire economy depended on coal, the courthouse has witnessed much litigation between labor and management. One dispute was not resolved within its walls but was instead settled on its front steps. “Two Gun Sid” Hatfield, who played a leading role in the 1920 “Matewan Massacre,” and his companion, Edward Chambers, were summoned to appear in court on August 1, 1921. As the men approached the entrance, members of the Baldwin-Felts Detective Agency, representing the coal companies, gunned them down.