He studied law and started his legal practice in Iran at the age of 24. The National Spiritual Assembly asked him to defend the oppressed Bahá'ís of Sháhrúd, where, on 8 August 1944, three friends had been martyred and 17 Bahá'í homes had been plundered and set on fire. 'Aziz defended them with great eloquence and undaunted courage, braving the vicious opposition of the clergy. Later he was asked to defend the Bahá'ís of Shiraz and still later those in Yazd. His unceasing endeavours won him the praise of the beloved Guardian who later designated him the "Shield of the Cause of God" and predicted that future historians would study his achievements.

In 1953 he and his wife Shamsi pioneered to Monte Carlo in Monaco to replace Mrs French who had passed away. While at this post he studied international law at the University of Paris-Sorbonne. In 1955 the Guardian appointed him to the Commission that appealed to the United Nations in Geneva and New York about the Iranian attempt to exterminate the Bahá'í community. In 1962 he became involved with the imprisoned Bahá'ís in Algeria and Morocco.

In 1968 Dr. Navidi became a representative of the Iranian Oil Company for its operations in the Indian Ocean and the family made their new home in Mauritius from where he worked to secure legal recognition of several of the new National Assemblies in the Indian Ocean region as he did with various African states. He fearlessly visited countries hostile to the Bahá'ís with no protection except his faith and his credentials as official lawyer to the Universal House of Justice with special status at the United Nations. His missions took him to Cameroon, the Central African Republic, Chad, the Congo, Gabon, the Gambia, Kenya, Madagascar, Senegal, Sierra Leone, Zaire, and many, many other countries throughout the world. He was successful time and again in persuading democratic governments and dictators alike to alter their laws and constitutions and to officially recognize the Bahá'í Faith. [BW20p866; Navidi, Dr. Aziz (1913-1987): Intrepid Pioneer, Knight of Bahá'u'lláh by Graham Walker; KoB341-344]