This thesis examined how cultural factors influence the success of cross-border mergers and acquisitions (M&A) between companies in the Benelux and Nordic regions. Despite geographic proximity and institutional similarity, these regions exhibited meaningful differences in leadership styles, communication patterns, and risk perceptions that can affect M&A outcomes. Drawing on 16 expert interviews and three illustrative case studies, this study applied a qualitative multiple-case approach to examine how culture shapes negotiation strategies, post-acquisition integration, and due diligence practices. The findings revealed that cultural dynamics played an increasingly important role across all deal stages. Dutch professionals were frequently described as direct and efficiency-oriented, while Nordic actors emphasized consensus-building and transparency. Belgian dealmakers exhibited a more hierarchical and risk-averse approach, often favouring formal legal structures. These differences affected not only negotiation and integration processes but also the perceived definition of success. Whereas academic literature often equates success with financial performance, interviewees pointed to long-term collaboration, trust, and employee retention as equally important metrics. The study contributes to international business literature by connecting classical cultural theories with real-world M&A practices and proposing a more multidimensional understanding of M&A success, one that encompasses cultural integration and stakeholder satisfaction alongside financial results. Practical implications include the need for structured cultural due diligence, culturally adaptive leadership strategies, and broader post-deal success measurement frameworks.