Preferential and free trade agreements (PTAs/FTAs) have long been recognized as pivotal instruments for fostering international trade, driving economic growth and strategic development through the reduction of tariffs and the facilitation of goods and services exchange. This study investigates the impact of recent PTAs/FTAs between the Islamic Republic of Iran and the Eurasian Economic Union (EAEU), specifically focusing on trade relations with the Republic of Kazakhstan. The primary research question addresses whether these agreements have yielded a measurable increase in bilateral trade flows between Iran and Kazakhstan. Furthermore, the study aims to comparatively analyze the strategic trade dynamics between Iran and the EAEU, with a particular emphasis on Russia and Kazakhstan. To address these objectives, this research employs a gravity model to quantify the impact of the PTAs/FTAs on trade flows. Additionally, the trade complementarity index (TCI) is calculated to assess the potential for mutually beneficial trade. The empirical findings demonstrate a statistically significant positive effect of the agreements on bilateral trade. However, comparative analysis reveals that the TCI between Iran and Russia exhibits greater temporal stability than that between Iran and Kazakhstan, suggesting a potentially more robust and consistent trade relationship. Based on these findings, the study argues that to fully capitalize on its geographical advantages and strengthen strategic trade ties with the EAEU, particularly Russia and Kazakhstan, Iran must prioritize the diversification and expansion of its industrial exports. Further, substantial investment in trade and transportation infrastructure is crucial for enhancing connectivity and reducing transaction costs. Finally, establishing Iran as a regional grain hub can significantly bolster its position in regional trade networks. The implementation of well-defined and strategically oriented trade policies is essential for maximizing the benefits of these agreements and solidifying Iran’s role in regional trade dynamics.