PurposeThe Brittelstand are innovative, family-owned firms that offer national and international opportunities in the United Kingdom (UK). These fast-growing businesses are customer-oriented and proud of family ownership and embeddedness of the businesses within communities. While Brittelstand firms are as likely to deploy open innovation models as non-Brittelstand firms, these firms' engagement with customers in regional and national markets and the ability to benefit from this collaboration contrasts with these firms' willingness to engage in open innovation.Design/methodology/approachUsing longitudinal data and regression analysis on 13,876 firms with 24,286 observations over 2004–2020, the authors develop and test a theoretical framework of open innovation in the Brittelstand. The authors' model explains the willingness and ability of the Brittelstand firms to engage in open innovation and benefit from it.FindingsThe authors' results show that Brittelstand firms are less willing than non-Brittelstand firms to collaborate with customers and universities, contrasting prior research on family firms, and distinguishing the innovation model of the Brittelstand from a family business model. The Brittelstand firms who are able to engage in collaboration with customers in domestic markets will outperform the firms' non-Brittelstand counterparts in innovation outputs.Research limitations/implicationsIn line with other studies, this study is associated with several limitations that open opportunities for further research that replicate and/or extends this study. First, this study is unbalanced panel data and the fact that some firms appear in the model only once from 2004–2020. The longitudinal study will allow to enforce causality of the relationship and examines the dynamics of open innovation in the Brittelstand. Second, the indicator on the extent and mechanisms of collaboration with customers could be better explained and measured, for example, using a scale indicator instead of a binary variable for knowledge collaboration across different types of partners and four geographical dimensions.Practical implicationsFirst, Brittelstand firms who are less likely to employ open innovation models nationally and with customers. However, those Brittelstand firms who decide to collaborate with customers nationally are more likely to increase the innovation sales compared to those firms that do not engage in such collaborations? This is an interesting and unexpected finding, which means that low willingness of cross-country and cross-regional collaboration for Brittelstand firms is not optimal and engagement in collaboration with customers in domestic markets is beneficial for innovation. Managers and policymakers may use this finding to design and re-design open innovation strategies managers and policymakers with customers within and across regions in the UK. Second, managers may benefit from the integrated view on the two drivers of firm innovation – collaboration with customers and the local embeddedness of such collaboration.Social implicationsThe authors' results show that Brittelstand firms outperform the firms' non-Brittelstand counterparts by adopting an open model of innovation with customers in domestic markets. This means that the most dynamic and fast growing Brittelstand firms are those who collaborate with customers for new ideas and innovation.Originality/valueThis study describes the phenomenon of the Brittelstand and investigates the link between open knowledge sourcing across different geographical proximities and partners and innovation outputs. First, the authors contribute to open innovation and resource-based view (RBV) literature in family firms by theorizing and empirically testing the open innovation model for the Brittelstand firms. The authors also debate that the Brittelstand firms should overcome this inertia of willingness to collaborate across heterogeneous external partners and convert regional/national embeddedness of the firms with customers into strengths for greater product innovation. Second, the authors contribute to family business literature by explaining how and why the Brittelstand firms can achieve greater innovation outputs. In doing so, the authors draw on the concept of familiness and local embeddedness.