Introduction to the Problem: Transnational crime has become one of the most pressing global challenges, demanding more cohesive mechanisms of international cooperation and legal enforcement. Purpose/Study Objectives: This study investigates and compares the institutional and procedural frameworks governing transnational criminal prosecution in Vietnam and the European Union (EU), with particular attention to mutual legal assistance, extradition, and cross-border evidence exchange. Design/Methodology/Approach: The research adopts a qualitative, comparative design grounded in Samuel’s (2014) theory of comparative law, drawing upon legislative texts, regional treaties, and institutional reports from UNODC, Eurojust, and ASEAN. Through this analytical lens, the study evaluates how both systems balance efficiency, sovereignty, and judicial trust. Findings: The findings reveal that Vietnam’s framework, centered on state sovereignty and diplomatic coordination, ensures national control but often suffers from procedural fragmentation and slower evidence transfer. In contrast, the EU’s supranational model – anchored in mutual recognition, direct judicial cooperation, and digital interoperability – delivers greater uniformity and timeliness, albeit with limited national discretion. Both systems, however, demonstrate strong alignment with global conventions such as UNTOC and ACTIP. Conclusion: The study concludes that Vietnam’s ongoing legal modernization could benefit from selectively adopting elements of the EU’s integrated structure, fostering enhanced efficiency, transparency, and regional judicial coherence within ASEAN’s evolving transnational justice architecture.