The purpose of this study is to establish the mediation of financial return between innovation and sustainability of small social entrepreneurship. Earlier research is limited in this perspective, and therefore this study focuses on filling the gap as far as the relationship between innovation and sustainability of social entrepreneurship is concerned. The research data for this study comes from Nigeria by adopting a Likert Scale questionnaire through a convenience sampling approach. In the data analysis, this research utilized SPSS ver. 25 and SmartPLS ver. 3.2.8? for descriptive statistics, structural equation modeling, and mediation analysis. At the end of the study, the findings show that there is a direct relationship between entrepreneurial innovation and its sustainability, which is mediated by financial return in the developing countries' settings. While this study has successfully established the clarity concerning the relationship between the chosen variables including, innovation, financial returns, and sustainability of social entrepreneurship in the developing countries, there is the need for further research due to the global significance of social entrepreneurship. The research discusses the limitation of the study and recommends future research to focus on comparative study between countries, gender divergence study, culture, and technological effects in social entrepreneurship.