On 17 September 2021, the Shanghai Cooperation Organization (SCO) approved Iran’s complete membership application 15 years after obtaining observer status in 2005. Iran is slated to receive full SCO membership in April 2023, marking its first move to join a significant regional organization since the 1979 Islamic Revolution. Iran’s future membership in the SCO brings many opportunities and challenges, which can affect its future growth and direction. This study focuses on Iran’s membership application to the SCO from 2005 to 2021 and analyzes the opportunities and challenges that Iran’s membership can bring to the organization. It uses a SWOT analysis of Iran’s diplomatic, information, military, and economic instruments of national power as it has used them in its application. Through this analysis, the study shows that overcoming sanctions is the primary driver of Iran’s push to join the SCO, and its instruments of national power are sufficient to contribute to security cooperation within the SCO’s framework. However, Iran’s membership may complicate SCO decision-making processes and fuel additional Western pressure on the SCO as an anti-Western alliance. It remains to be seen if Iran’s membership will be a game-changer for the SCO in achieving its goals. Ultimately, as the SCO matures as an organization, it gives the impression that the Western-led international order is one of many viable frameworks for the international order. With its disadvantaged position in the Western-led international order, Iran may seek to play a more prominent role in shaping an alternative where it can protect and forward its interests.