It is a three-story, Richardsonian Romanesque style Indiana Oolitic limestone and terra cotta building.

A wooden structure was utilized when Knox became the county seat in 1850, being replaced with a larger, brick building in 1858.

The courthouse presently contains the offices for zoning, health, the Council on Aging, the Court Clerk, the law library, the Jury room, probation, and Judges' Chambers, and the courtrooms.

The entryway has a balustrade balcony, on a corbel table, spanning a one-story entry with gargoyle light fixtures.

[2] Flanking the central pavilion are single bays, with a pair of windows topped by a round arch at the ground level.

[2] Although the third floor double-hung windows are round-arched, their heads are Gothic-arched, with rock-faced voussoirs and ornate springers.

The lower section contains paired, deepset, compound, round-arched windows, divided horizontally into four lights.

[2] The courthouse interior has hardwood and ceramic-tiled floors, plaster and panel wall treatments, and ornate cornice and pilaster capitals.

The staircase is accented by ornamental iron balusters, marble steps, and a patriotic ceiling painting of Liberty located between the first and second floors.

Ionic capitals, with polychrome gilding, eagle, and shield are found on hall columns and pilasters.