This paper traces the history of the evolution of the Yoruba language as a written language. Up till the 19th century, the Yoruba language existed only as a spoken language. The Christian religion played a vital role in this evolution as the majority of those involved in the setting out of the rules were ministers of God. Bishop Ajayi Crowther of the Christian Missionary Service (C.M.S) was in the forefront of this project. Other ministers of God who participated in this project included those of Britain, France, Germany and America. Their first breakthrough occurred when they translated the Holy Bible into Yoruba language. The difficulties they faced and how these were surmounted have been presented. Some of the rules and guidelines they evolved are in use till the present day. Efforts of modern day researchers and Governments of the Yoruba speaking people of Nigeria have also been documented as the revolution of the written language continued until the year 1974. It will be seen in conclusion that the Yoruba language stands equal to other languages in the world both in the spoken and written form.