This research aimed to assess the operational and environmental performance of small and medium-sized enterprises (SMEs) in Nigeria in relation to their adoption of green supply chain management practices (i.e. green purchasing, green marketing, green packaging, green design and distribution). The survey-based study involved the entire population of SME operators in Southwest Nigeria, totaling 1,901 individuals (i.e. entrepreneurs). Through the use of stratified random selection methods, a sample size of 330 was chosen. Structural and measurement models were used to analyse the collected data. The findings of the study indicate that green distribution significantly influences the environmental performance of SMEs. Furthermore, the results demonstrate that green procurement has a positive impact on the environmental performance of SMEs. Consequently, it can be inferred from these findings that there is a positive correlation between the efficiency and effectiveness of green supply and procurement practices among Nigerian SMEs. To enhance both their overall operational performance and their environmental performance specifically, the study recommends SME operators in Nigeria to adopt green supply management practices for sustainability. This would contribute to improving the efficiency and efficacy of their green supply and procurement activities.