After the independence of the Central Asian (CA) republics, Iran has tried to develop its relations with these sates, especially with Tajikistan. The development of bilateral relations between Iran and Tajikistan has been very important for both sides. But after nearly 30 years of political relations between Iran and Tajikistan, bilateral relations have not developed much and have faced numerous limitations. By adopting Rosenau’s theory, the current study aims at investigating Iran’s foreign policy (FP) toward Tajikistan and the factors influencing the bilateral relations between the two countries. The present paper argues that societal, governmental, idiosyncratic, and role variables, respectively, have hindered the development of bilateral relations between Iran and Tajikistan. Finally, systemic variables have had the least influence on Iran’s relations with Tajikistan, and the results show that the U.S. and its sanctions have not had insignificant effect on Iran–Tajikistan bilateral relations, and in terms of the systemic variables, Iran has faced more opposition from China than any other country in the development of relations with Tajikistan.