The first of Floyd County's courthouses was a two-story Greek Revival building with a gable roof that was constructed during the years 1857 through 1861. This first courthouse, distinguished by its square tower, dome, and spire over the entrance gable, was designed by the architect Theodore Mix. The building was destroyed by fire in 1881, and it was replaced in 1881–1882 by a larger building in the Italianate style. The second courthouse was torn down in 1939 and it was replaced by the present structure.
The architects Hansen and Waggoner of Mason City supplied a sparse, puritanical version of the 1930s PWA style. A central pavilion projects slightly from the front facade of the building, and at its base is the building's main public entrance. The windows of the four floors are grouped in recessed vertical bands. The surface of the structure is of tan brick, while Bedford limestone and polished red granite were used for the raised basement and for external and internal trim.