After the disintegration of the Soviet Union in December 1991, and the subsequent geopolitical changes in the northern borders of the I. R. of Iran, Azerbaijan Republic gained more importance in Iran’s foreign policy. Because of the historical and cultural linkages, the two countries could not ignore each other’s security threats. There are many common elements that shape Iran’s foreign policy attitudes towards the Republic of Azerbaijan Republic and vice versa. The main research question to be answered in this asks: What are the fundamental causes of securitization of Iran - Azerbaijan Republic’s relations since 1995? Using a hermeneutic - interpretive approach, the authors examine the underlying causes which have led to the transformation of the nature of their bilateral relationship. Their main conclusion is that since 1995, a set of physical, perceptual, ideational and normative factors, like ethnical identity, political Islam in Iran, the secularism in Azerbaijan republic, and attitudes toward social identity of the World System, has changed the focus of their relations from cooperation to securitization.