Purpose Digital servitization research has focused on how manufacturing firms use digital technologies to change business models and offer smart services; less attention has been devoted to the degree to which external actors in the existing ecosystem accept these smart services. Therefore, the authors pose the following research question: How does a manufacturing firm introduce and gain acceptance of new smart services within an established ecosystem? Design/methodology/approach Building on servitization, ecosystem and legitimacy theories, this paper addresses the research question through an in-depth case study of a world-leading original equipment manufacturer that is currently developing and introducing new smart services in its existing ecosystem. Findings The findings suggest that external actors emphasize different types of legitimacy in deciding whether to accept a new smart service. The findings also show that the type of legitimacy required to gain acceptance changes throughout the development of the smart service, from the definition of the value proposition to the design and delivery of the service. Practical implications This study can assist smart service providers in identifying which type of legitimacy is important for each ecosystem actor and strengthening these types of legitimacy to gain acceptance from the ecosystem. Originality/value This study develops a framework to help describe the thresholds for acceptance of a smart service through the development phases, as well as to indicate the types of legitimacy that smart service providers must relate to when seeking to gain acceptance for their new offering.