This systematic literature review examines how organizations utilize their internal resources to attain sustained strategic advantage (SSA) in a dynamic and competitive environment. The review emphasizes understanding the strategic mechanisms through which resources- including human capital, knowledge, routines, and digital infrastructure are implemented over the long term to sustain competitiveness. Specifically, the study seeks to⁠ investigate mechanisms through which firms transform resources into long-term competitive advantages, analyze methodological approaches in existing research, and highlight promising directions for future inquiry. The PRISMA 2020 and PCC (Population-Concept-Context) guidelines are utilized to yield 3702 records from a comprehensive search of five scholarly databases. By applying stringent inclusion criteria, 43 peer-reviewed articles published between 2017 and 2025 were included for review. The results highlight five significant themes: the move from resource ownership to orchestration, the integration of leadership cognition and knowledge, the development of hybrid resource strategies, sustainability as a strategic resource, and the contextual factors in emerging markets. The findings suggest that SSA relies on flexible positioning and adjustment of internal resources rather than fixed possession. Future research should address longitudinal, cross-regional studies and discover the roles of digital technologies, soft assets, and hybrid strategies to expand the consideration of internal resource leveraging.