Johnston County Courthouse is a historic courthouse building located at Smithfield, Johnston County, North Carolina. It was designed by noted architect Harry Barton and built in 1920-1921. It is a three-story, rectangular steel frame building with a cut stone veneer in the Classical Revival style. It features a four-column portico in antis, a tetrastyle pedimented portico, and a stone balustrade at the roofline. It was listed on the National Register of Historic Places in 1979.