Abstract: Background and Objective: This study analyzes the roots’ supply capacity and response for smallholder cassava farmers supplying commercial starch processors in Nigeria. Among the specific objectives were to identify the key production and marketing challenges and examine the factors driving roots’ flow from farmers to processing factories. Materials and Methods: A multi-stage random sampling technique was used to select 96 farmers from the enlisted clusters in eight cassava-growing states. Data were analyzed using descriptive and inferential statistics and multivariate regression techniques. Results: Initial characterization revealed that 22.9% of all farmers were women, 32.3% into full-time farming and 97.9% married. About 80.0% of the farmers’ total produce was sold to various markets but only 61.1% of farmers supplied part of their produce to the starch factories. Yield (p<0.01), experience (p<0.01), farm size (p<0.01), commercialization (p<0.01), varieties type (p<0.01), factory gate price (p<0.01) and training (p<0.01) had significant positive influence on marketed surplus while the influence of open market price (p<0.01) was negative. Production cost, transport and logistics, dearth of fertilizer, labour and capital were the key production challenges while transport cost, distance and small size of markets were the key marketing challenges. Conclusion: Policies and programmes capable of promoting high yield and output, targeting farmers with proven experience, large farm sizes and demonstrated will to commercialize and offering competitive factory gate prices were ways of increasing flow of roots to starch processing factories. The significant negative effect of the open market price implied that inasmuch as the starch processors’ price remained less attractive and competitive vis-à-vis the price elsewhere, the problem of roots’ leakage would persist and the factories would continue to operate below capacity. The study recommended provision of best farm management package of practices including improved cuttings, regular training and retraining, agro-inputs’ credit, relevant extension and monitoring support services to promote farmers’ efficiency and roots’ flow. As big-time investors, the starch processors should show more commitment to cassava value chain development through direct assistance to farmers in opening of lands, purchasing or leasing of tractors and subsidizing transport facilities especially during harvesting, so as to curtail the farmers’ tendency to divert roots to alternative markets.