In 1854, Cunynghame served as Assistant Quartermaster-General to the first division, and was present at the affair of Bulganac and was present at the battles of the Alma, Balaclava, Inkerman, Chernaya, and at the Siege of Sebastopol. He was mentioned in despatches, received the Crimean medal with four clasps, the Turkish medal, was appointed a "légionnaire" of the Legion of Honour, the third class of the Order of the Medjidie, and was created a Companion of the Order of the Bath (CB).