Vietnam officially joined the Association of Southeast Asian Nations (ASEAN) on July 28, 1995, marking an important milestone in the expansion of Vietnam’s foreign relations and international integration during the Doi Moi period. This article analyzes the role of the ASEAN factor in Vietnam’s foreign policy during the 1995-2005 period, focusing on the impact of ASEAN participation on the expansion of cooperative relations, regional integration, and the pursuit of Vietnam’s foreign policy objectives. The findings show that the ASEAN factor not only contributed to expanding Vietnam’s foreign relations but also provided an environment, framework, and regional norms of cooperation through which Vietnam could fulfill its commitments as a member. Throughout its participation in ASEAN, Vietnam proactively promoted its role as an active member, respected and adhered to common principles and norms, while maintaining an independent, self-reliant, proactive, and flexible foreign policy, balancing national interests with the requirements of regional and international integration. The experiences gained during the 1995-2005 period remain significant for Vietnam’s continued efforts to expand and enhance the effectiveness of its international integration.