Despite decades of research and advances in strategic planning, organizations continue to struggle to convert strategic intent into realized outcomes. While traditional explanations focus on weaknesses in planning, leadership, or organizational culture, emerging evidence suggests the strategy–execution gap is primarily driven by misalignment between formal systems and informal networks of influence. This study employed a systematic literature review using the PRISMA 2020 framework to synthesize findings from 60 empirical studies published between 2006 and 2026 across diverse industries and contexts. The analysis identifies four key mechanisms of execution failure. These include divergence in sensemaking across hierarchical levels, which leads to inconsistent interpretations of strategic priorities; fragmentation of communication networks, which disrupts coordination and reinforces silos; the rise of informal “shadow governance” that shifts decision-making away from formal hierarchies; and silent failure, where strategic initiatives gradually erode without detection or corrective action. Collectively, these findings support a reconceptualization of strategy execution as a network-mediated process rather than a linear, top-down cascade. The framework highlights the central role of informal relationships, social capital, and influence dynamics in shaping outcomes, offering a more integrated explanation of why execution gaps persist and how they may be addressed.