•Digital platforms extensively transform business models in Industry 4.0 contexts.•Especially value propositions, revenue streams, and key partners are changed.•Inter-company and customer relationships also undergo significant alterations.•The results vary between different industry sectors and company sizes.•An ecosystem perspective enables a differentiation between platform roles and types. Being successfully applied in business-to-consumer industries for quite some time, digital platforms only recently have found their way into the industrial business-to-business world. However, rapid developments, particularly in the context of Industry4.0, have indicated enormous potentials from digital platforms for business models and inter-company relationships – fields of particular importance in industrial marketing. Motivated by a lack of empirical insights and calls from academia and practice, this paper sheds light on how digital platforms change industrial firms’ business models and inter-company relationships. We applied an exploratory case study design and analyzed a unique sample of 11 platform cases from the United States and Germany, differentiating between platform types and roles. The study reveals recurring themes in business model innovation and inter-company relationships. The results were elicited using a quasi-statistical approach, discussed and interpreted against the backdrop of the current state of research on platforms, business models, and industrial marketing.