This study empirically examined if cooperative societies is an instrument for poverty alleviation and sustainable development in South-East, Nigeria. The study is vital as it portrays the extent to which poverty alleviation and sustainable development are ensured and attained through the activities of cooperative societies. Three hypotheses were formulated to guide the investigation and the statistical test of parameter estimates was conducted using OLS regression model. The study employed Survey Design in the data analysis. Primary data was used for the study and was obtained through questionnaire survey administered to 30 selected cooperative societies in 5 state capitals in South-East Nigeria. The findings generally indicated that cooperative societies have contributed to poverty alleviation and sustainable development in Nigeria at 1% level of significance. Based on this, the study concludes that cooperative societies serve as instrument for poverty alleviation and sustainable development in South-East, Nigeria. In lieu of this, the study suggests that cooperative societies in Nigeria need government assistance to sustain them in their role of poverty alleviation through training, increasing their financial base, access to land, agricultural inputs, and education of farmers among others. This can be achieved by organizing regular training workshops and symposiums for farmer cooperative societies as well as instituting government regulatory and administrative measures to boost the activities of cooperative societies. These measures when carried out by the appropriate government agency will help to minimize cases of financial misappropriations associated with cooperative societies. Hence, the study contributed to knowledge by modifying existing models, introducing new variables and updating literature on the subject.