Blended finance has become a vital tool for mobilising resources into enterprises in developing economies, yet its ability to stimulate sustained product innovation remains uncertain. This study investigates how knowledge management (KM) practices enable blended-finance-backed firms to convert financial support into innovation outcomes. Guided by the knowledge-based view of the firm, the research focuses on FarmCrowdy, a Nigerian agri-tech enterprise that has benefitted from blended finance. A cross-sectional survey was conducted with 46 employees, representing a near census of the organisation. Reliability tests confirmed strong internal consistency (Cronbach’s α ≥ 0.81). Regression analysis revealed that KM practices significantly predict product innovation (R² = 0.435, β = 0.66, p < 0.001). Among KM dimensions, knowledge sharing exerted the strongest influence (β = 0.38, p = 0.002), followed by knowledge application (β = 0.32, p = 0.004) and knowledge creation (β = 0.27, p = 0.019). The findings show that capital inflows alone are insufficient to guarantee innovation; effectiveness depends on how enterprises manage and apply knowledge. The study contributes to development finance literature by positioning KM as a central enabler of innovation in blended-finance enterprises and recommends that development finance institutions embed KM capacity-building into their support frameworks.