O Apêndice F do O Senhor dos Anéis ("As Línguas e os Povos da Terceira Era") tem isto a dizer:
It is said that the Black Speech was devised by Sauron in the Dark Years, and that he had desired to make it the language of all those that served him, but he failed in that purpose. From the Black Speech, however, were derived many of the words that were in the Third Age wide-spread among the Orcs, such as ghâsh 'fire', but after the first overthrow of Sauron this language in its ancient form was forgotten by all but the Nazgûl. When Sauron arose again, it became once more the language of Barad-dûr and of the captains of Mordor. The inscription on the Ring was in the ancient Black Speech, while the curse of the Mordor-orc in II, 53. was in the more debased form used by the soldiers of the Dark Tower, of whom Grishnâkh was the captain. Sharku in that tongue means old man.
Essa é a resposta, então; Sauron desenvolveu-o no final da Segunda Era, quando ele estava dominando grande parte da Terra-média. Ele não conseguiu impor seu uso entre todas as suas criaturas, mas (especialmente perto do final da Terceira Era) seus minions mais poderosos a consideraram como sua principal, senão sua linguagem exclusiva.