Nigeria’s informal commercial economy represents a critical yet underserved segment of the national financial ecosystem, characterized by fragmented merchant profiles, cash-dependent transactions, and limited access to formal financial services. This paper proposes a scalable merchant acquisition model tailored to enhance payment platform penetration within this sector. Grounded in an integrative review of fintech adoption theories and informal market dynamics, the model emphasizes key adoption drivers, trust, accessibility, cost-effectiveness, and ease of use, and incorporates personalized onboarding, incentive mechanisms, and continuous support structures. Scalability is addressed through adaptability to regional and merchant heterogeneity, sustainable operational practices, and robust monitoring frameworks. Implementation considerations focus on overcoming infrastructural and literacy challenges through strategic partnerships with local agents and community influencers, alongside fintech collaborations. The model contributes theoretically by expanding acquisition frameworks to informal economies and practically by offering fintech providers actionable strategies for inclusive growth. Future research directions include empirical validation, integration of emerging technologies, and policy engagement to refine and scale the approach. This foundational framework aims to bridge financial inclusion gaps and catalyze digital payment adoption, fostering economic transformation across Nigeria’s informal commercial landscape.