J. Ambler Johnston was born in 1885 and was a 1904 graduate of Virginia Agricultural and Mechanical College and Polytechnic Institute. He also earned a master of science degree in 1905 from VPI. Johnston resided in Richmond, Virginia, where he served as a charter member of the Richmond Rotary Club and was a Civil War scholar. He died in 1974.

William Leigh Carneal, Jr., was born in Richmond on October 24, 1881, and graduated in 1903 from the Virginia Military Institute. He began his architectural practice around 1906 following a three year stint as a clerk in his father's company, Sitterding-Carneal-Davis Company. He died in 1958.

In 1908, Carneal and Johnston combined offices. The firm's first building was the original McBryde Hall on the VPI campus, completed in 1917. The firm helped to incorporate the Collegiate Gothic style to the campus landscape. For a brief period, the firm included a third partner and was known as Carneal, Johnston, & Wright. Both Carneal and Johnston retired in the 1950s. In 1999, the surviving firm of Carneal and Johnston merged with Ballou, Justice, & Upton Architects.