Grounded in upper echelons theory, this research contributes to the current literature on SME digital transformation by leveraging empirical data from 372 SMEs in an emerging economy. The study investigates the influence of overconfident managers on digital transformation and its subsequent impact on sustainable competitive performance, with digital culture playing a moderating role. Our findings reveal that managerial overconfidence significantly influences digital transformation and sustainable competitive performance in SMEs. Digital transformation serves as a significant mediator of the relationship between managerial overconfidence and sustainable competitive performance. Additionally, digital culture strengthens the association between managerial overconfidence and digital transformation. Based on these insights, SMEs need to be aware of managerial traits and, in particular, need to focus on overconfident managers to embrace digitalization and enhance performance.