The intensifying US-China power competition in the Indo-Pacific region poses significant challenges to regional countries' political and security situations. Vietnam, with its crucial geostrategic position in Southeast Asia and intertwined national interests, employs a balancing foreign policy strategy to navigate relations with these major powers. This paper analyzes the principles and modalities of Vietnam's balancing strategy in the US-China rivalry. Vietnam pursues a flexible and diversified foreign policy, establishing strategic partnerships with both the US and China across various domains while leveraging multilateral frameworks and institutions to promote security cooperation and maintain regional peace and stability. The findings have implications for assessing how Vietnam can effectively implement its balancing strategy amidst the complex US-China rivalry dynamics. This is particularly challenging for a small country like Vietnam, given the substantial power asymmetry and vulnerability inherent in such imbalanced relationships.