Established in 1861, Humboldt County took its name from the Humboldt River, which runs through the territory. The river itself was named after Baron Friedrich Heinrich Alexander von Humboldt. Although the first county seat was located in Unionville, officials did not build a permanent courthouse until the seat of government shifted to Winnemucca in 1873.

The county hired building supervisor James Z. Kelly and a Stockton contractor named Murphy for the project. The rectangular brick building was completed in 1874 at a cost of $47,800.

Exhibiting Italianate elements, the building's exterior consisted of a five bay facade with elongated windows, interior side chimneys, and a cupola in an octagonal shape. A balcony on the second floor elevation rested over the main entrance. Fire destroyed the structure in 1918.

Officials accepted designs from Frederick DeLongchamps for a new courthouse in 1919, and set a limit of $150,000 for the project. Construction was finished in 1921 under the supervision of Lehman A. Ferris.

Built at the site of the former courthouse, the ninety-by-ninety-foot, two-story building demonstrates a Neoclassical style with a Beaux-Arts influence. The exterior features a pedimented portico supported by Corinthian columns, along with matching brick pilasters capped with terra cotta. Sculpted eagles with outstretched wings decorate the spaces above the doorways. The interior contains a marble staircase, and a two-story atrium with ionic columns that support a dramatic leaded-glass ceiling. The Humboldt County courthouse intimidated the newly created rival, Pershing County, which subsequently sought a less expensive, but nevertheless remarkable design for its courthouse.

Later additions to the Humboldt County courthouse include structures housing city offices and the county sheriff's department. DeLongchamps designed further additions for the building starting in 1949, but they were not implemented. In 1976, a passageway was added connecting the courthouse with the office building in the rear.