Start-ups operate in a highly competitive environment, surrounded by companies that offer similar products and services. In this context, collaboration between competitors has been found to help companies reduce risk and share costs, resources and expertise. Despite its relevance, coopetition (i.e. the simultaneous pursuit of cooperation and competition) in entrepreneurship has attracted little scholarly attention. This study aims at filling this theoretical and empirical gap by exploring the impact of coopetition on the performance of start-ups. Drawing on the existing literature, this study also considers innovation and knowledge sharing as key factors that can shape business performance. The analysis is based on qualitative comparative analysis (QCA) because the focus is on the combined effect of the determinants of firm performance rather than their net effects. This approach enables identification of different start-up strategies. The results indicate that coopetition and innovation are important to positively influence market performance. However, knowledge sharing is only relevant when coopeting start-ups either have solid market experience or are highly innovative.