Purpose People with complex health conditions must often navigate landscapes of uncoordinated public, private and voluntary health-care providers to obtain the care they need. Complex health conditions frequently transcend the scope of typical health-care service systems. The purpose of this paper is to explore and characterize such unique assemblages of actors and services as “user-defined ecosystems”. Design/methodology/approach Building on literature on customer ecosystems, this paper introduces the concept of the user-defined ecosystem (UDE). Using an abductive approach, the authors apply the concept in an interpretive, qualitative study of ten families with special needs children. Findings This study uncovers complex UDEs, where families actively combine a broad range of services. These ecosystems are unique for each family and extend beyond the scope of designed service ecosystems. Thus, the families are forced to assume an active, coordinating role. Research limitations/implications This paper shows how to identify ecosystems from the user’s point of view, based on the selected user unit (such as a family) and the focal value-creating function of the ecosystem for the user. Social implications This paper highlights how service providers can support and adapt to UDEs and, thus, contribute to user value and well-being. This can be used to understand users’ perspectives on service and systems in health and social care. Originality/value This study develops the concept of the UDE, which represents a customer-focused perspective on actor ecosystems and contrasts it with a provider-focused and a distributed perspective on ecosystems. This study demonstrates the practical usefulness of the conceptualization and provides a foundation for further research on the user’s perspective on ecosystems.