Co-operative societies ought to be inclusive, member-focused organizations that genuinely support the development of sustainable livelihoods. They are intended to operate through the development of strong interpersonal relationships among members, effective access to market opportunities, consistent support for entrepreneurs, and active participation in democracy. However, in many Nigerian co-operative societies, there appears to be a stark difference between these expectations and the actual outcomes. The study therefore examined the impact of co-operative entrepreneurship support and assessed the impact co-operative social capital development on members’ business performance and members’ social inclusion. Descriptive survey research design was employed, and 340 co-operative members sampled using a multistage sampling technique. Data were collected through a structured and validated questionnaire, which yielded a reliability coefficient of 0.83 through the test–retest method. Descriptive statistics, including frequencies, percentages, means and standard deviations were used for data analysis, while hypotheses were tested using simple linear regression at 0.05 significance level with SPSS version 27. The findings revealed that co-operative entrepreneurship support (β = 0.991, p < 0.05) and co-operative social capital development (β = 0.988, p < 0.05) had significant impact on their level of members’ business performance and members’ social inclusion in Nigeria. The study recommended improving support for entrepreneurship by routinely offering members affordable financing options, mentorship and ongoing business training and also strengthening social capital through co-operative activities, ongoing education about co-operative values, and trust-building initiatives.