Purpose: This study aims to assess the mediating effect of sustainable competitive advantage (SCA) on the relationship between organisational innovativeness (OI) and performance of small- and medium-sized enterprises (SMEs) operating in Konya, Turkey. Design/methodology/approach: A survey method is used to collect the necessary data for this research. A total of 264 respondents from 83 SMEs partook in the study. In choosing the sample size, both purposive sampling and simple random techniques are used. The data gathered are analysed using SPSS program and Hayes PROCESS macro v.3.4.1. Findings: The results of the analyses reveal that OI has a statistically significant positive effect on SCA and firm performance (FP). Moreover, SCA is found to have a mediating effect on the relationship between OI and FP. Practical implications: Policymakers and management of SMEs need to show great commitment to innovativeness and relate it to SCA to create superior customer value, thereby leading to a holistic and long-term FP. Originality/value: This study brings to the fore empirical evidence on how SCA serves as a mediator between OI and FP. It also contributes to the literature by focusing on three distinct but related variables. The study makes theoretical contribution by highlighting the role of the resource-based theory in enhancing business performance and SCA through strategic internal resources and innovative activities.