Cassava value addition efforts suffer a serious setback in Nigeria despite huge production potentials due to a weak linkage between producers and processors. Psaltry cassava outgrower scheme thus emerged as a model to facilitate the needed linkage and boost farmers' productivity. The need to understand how the Psaltry model has encouraged increased cassava productivity informed this study on the effects of Psaltry cassava outgrower scheme in enhancing smallholder productivity in Oke-Ogun area of Oyo State, Nigeria. Pre- and post-intervention combined with treatment and control group designs were used for the study. Data were collected from 232 outgrower and 49 non-outgrower farmers using interview schedules on their socio-economic characteristics, access to agri-support services, change in cassava productivity due to participation in the Psaltry scheme and challenges faced in the scheme. Data were analysed using descriptive statistics and regression analysis at α 0.05. Outgrowers were aged 46.5±17.3 years, had 2.8±1.1 years of experience with Psaltry, mostly male (65.9%), belonged to farmers group (96.1%) and had at least primary school education (60.8%). Non-outgrowers had close socio-economic characteristics with outgrowers. Assured markets (90.5%) and training on post-harvest handling of crops (69.9%) were most common among the supports received from Psaltry. Long bureaucratic process involved in documentation (2.23±0.7) ranked as the most severe constraint faced in the scheme. Total cassava harvested and productivity among outgrowers increased from 30,950.89±31,133.48kg to 106,116.88±96,926.01kg and 5,649.2±3835.3kg/Acre to 9,143.6±8799.1 kg/Acre before and after participating in Psaltry scheme, respectively. Productivity was higher among outgrowers (9,143.6±8799.1 kg/Acre) than non-outgrowers (1,047.24±4,789.34kg/Acre). Membership of group (β=0.319) and length of involvement in Psaltry scheme (β=0.157) positively and significantly influenced out-growers change in cassava productivity. Psaltry outgrower scheme had stimulated beneficiary’s smallholder farmers towards higher productivity through assured markets for their cassava produce. A scale-up of the Psaltry model has prospects for transforming smallholder farmers to commercial producers.