Background: As small- and medium-sized enterprises (SMEs) are the primary source of job creation in Nigeria and contribute 48% of the country’s gross domestic product (GDP), their performance must be enhanced and sustainability ensured. The article suggests that through competitor orientation and proactiveness, SME managers and owners can achieve competitive advantage which ultimately promotes firm performance.Aim: The article aims to examine how competitor orientation and proactiveness in competitive advantage enhance the performance of SMEs in Nigeria.Setting: The study focused on registered SME owners and managers who are operating in Nigeria, using Lagos State as a case study.Methods: This study was conducted through administering questionnaires to owners and/or managers of SMEs as the unit of analysis. A quantitative research design was used with stratified and simple random sampling as the sampling method, with the sample comprising 100 SME owners and/or managers.Results: The results of the study indicated that competitive advantage mediates the relationship between competitor orientation, proactiveness and SMEs’ performance indirectly. It further revealed that competitor orientation and proactiveness have significant effects on SMEs’ performance.Conclusion and contribution: The article reveals how competitive advantage, which is influenced by competitor orientation and proactiveness, contributes to increased SMEs’ performance in SME sectors. Thus, to gain a competitive edge over their rivals, the study recommends that SME owners and managers consider competitor orientation and proactiveness more seriously, as these factors ultimately boost their performance.