Globalization is driving the increasing adoption of mergers and acquisitions (M&A), with global M&A transactions reaching a record high of US$5.9 trillion across 63,000 deals. Organizational integration was identified as one of the most significant factors in M&A performance. To prevent business losses and enhance the performance of M&A, we investigated how organizational integration correlates with M&A performance. A methodology for integration management was developed to analyze the direct and indirect effects of organizational integration on M&A performance. The study developed hypotheses from empirical data and assessed six constructs using structural equation modeling. The quantitative survey included employees who participated in M&A in the past decade. Primary data from a 203-respondent sample was gathered using a structured questionnaire. The results demonstrated that organizational integration has a significant and positive influence on influences synergy, diversification, and competitive strategy. Organizational performance was significantly influenced by synergy, diversification, and competitive strategy. M&A performance was found to significantly influence competitive strategy and organizational performance. All hypotheses are supported except the hypothesis of synergy towards M&A performance; however, there is still indirect influence through organizational performance. The findings emphasize the importance of organizational integration in improving M&A success; it fills a substantial gap in the existing literature by presenting empirical evidence of the direct and indirect effects of organizational integration.