South Sudan's post-conflict economy presents unique challenges for entrepreneurship, with a nascent private sector operating in an environment of institutional fragility and limited financial inclusion. Understanding how enterprises develop viable business models under such constraints is critical for fostering sustainable economic development in Sub-Saharan Africa. This study aims to identify and analyse the innovative business model strategies developed by entrepreneurs in South Sudan to navigate a challenging operating environment. It seeks to understand the drivers, components, and perceived efficacy of these adaptations. A sequential explanatory mixed-methods design was employed. First, a quantitative survey of 187 registered small and medium enterprises was conducted to map prevalent business model characteristics. This was followed by 24 in-depth qualitative interviews with a purposively selected sub-sample of entrepreneurs to explore the rationale and implementation of identified innovations. Quantitative analysis revealed that 68% of surveyed firms had implemented at least one major innovation in their revenue model or value chain structure within the previous period. Thematic analysis of interview data identified a dominant strategy of 'embedded barter and trade', where firms integrate non-monetary exchange and social capital into formal transactions to overcome liquidity constraints. Entrepreneurs in this context demonstrate significant ingenuity in business model innovation, primarily as a pragmatic response to systemic market failures rather than technological advancement. These adaptive strategies are crucial for enterprise survival and growth. Policymakers and development finance institutions should design support mechanisms that recognise and leverage indigenous business model innovations, particularly those enhancing liquidity. Future research should longitudinally track the scalability and long-term sustainability of these adaptive models. business model innovation, entrepreneurship, post-conflict economies, mixed methods, Sub-Saharan Africa This paper provides the first systematic, mixed-methods evidence of the specific business model adaptations developed by South Sudanese entrepreneurs, offering a novel dataset and typology for a severely under-researched economic context.