In the context of recurring global crises, antifragility offers an important lens for understanding how SMEs can not only withstand shocks but also improve through them. While resilience has been widely studied, less is known about the antecedents of antifragility and how they translate into firm performance. This study develops and tests a model examining how digital technology capability, relational capability, and slack financial resources shape SME financial performance through antifragility. Drawing on the resource-based view and dynamic capabilities perspective, we argue that strategic resources do not directly enhance performance under uncertainty but instead operate through antifragility as a mediating mechanism. The model is tested using survey data from 203 Iranian service-sector SMEs and analyzed using partial least squares structural equation modeling. Results show that digital technology capability, relational capability, and slack financial resources significantly enhance antifragility. Only slack financial resources have a direct effect on financial performance, while digital and relational capabilities influence performance indirectly through antifragility. The findings highlight antifragility as a key mechanism linking resources to performance in uncertain environments. This study contributes to the emerging antifragility literature by identifying antifragility as a key mechanism through which strategic resources are transformed into superior financial performance in SMEs.