The parlor in the Johnston House is an important room for entertaining visitors. It has the most elaborate woodwork in the house and rare stenciled decoration, which is not common in 19th-century homes in Virginia. During restoration in 1998, the stenciled decoration was discovered after the wallpaper was removed. The room was painted to look like French wallpaper, with swags at the top and a vine and berry border above the chair rail. The wall under the chair rail was originally painted with a column design in orange and peach, and one section of it has been restored.

Sometime before 1930, the fireplace mantle was removed and the room was remodeled as a bedroom. During restoration, the present mantle was installed and narrow oak floorboards were removed to reveal the original pine flooring.

Except for Dr. Johnston's desk, the furnishings in the parlor are either gifts or loans from local residents. The rosewood-veneered square grand piano is from New York and was purchased from Nash & Woodhouse in Richmond before the Civil War. It was transported by wagon to Pearisburg and stood in the Western Hotel for many years. Other furnishings in the parlor include a pedestal table with matching maple armchair and glider, a walnut piecrust table, and a Victorian sofa dating to circa 1900.