The acceleration of digital transformation has profoundly reshaped the operational logic and market engagement patterns of Micro, Small, and Medium Enterprises (MSMEs). Yet, adaptation to online marketing among Baby Boomer and Generation X entrepreneurs remains uneven and context-dependent. This systematic literature review (SLR) synthesizes findings from fourteen peer-reviewed studies published between 2019 and 2025 to examine how these generational cohorts navigate the transition from traditional to digital marketing ecosystems. Following the PRISMA 2020 protocol, the analysis integrates multilevel perspectives encompassing individual (digital literacy, motivation, and self-efficacy), organizational (leadership, orchestration, and digital transformation), and ecosystemic dimensions (policy, infrastructure, and inclusion). Results highlight that Generation X entrepreneurs demonstrate performance gains through competence-driven adoption and motivational reinforcement, while Baby Boomers exhibit stronger engagement through emotionally familiar and trust-based channels such as WhatsApp and Facebook. Generational tensions in transformation processes can be mitigated through transparent leadership communication, structured operational routines, and cross-generational mentoring. From these insights, the MOSAIC framework Motivation & Skills, Orchestration, Safety & Trust, Affiliation-based Content, Integration of Channels, and Cashless Conversion is proposed as an inclusive roadmap for sustainable MSME digitalization led by senior cohorts. This review contributes to bridging Generational Cohort Theory, Self-Efficacy Theory, and Dynamic Capability Theory, thereby offering theoretical integration and practical policy implications for advancing intergenerational digital transformation.