Technical progress has enabled companies to offer smart services. In the mobility sector, emerg-ing door-to-door (D2D) mobility integrators promise to provide highly individualized, dynamic, and context-aware mobility service by bundling different mobility services, such as car-sharing and public transport. These D2D mobility integrators are well-positioned to facilitate access and use of non-private car-based mobility and thus to contribute to solutions to major challenges facing cities around the world, such as traffic congestion and air pollution. However, D2D mo-bility integrators struggle to attract mobility providers to their service ecosystem. This research applies the concept of legitimacy, which originates from institutional theory, and service-dominant (S-D) logic to analyse the current embeddedness of mobility providers in ser-vice ecosystems and the underlying institutional arrangements as a possible barrier to entering into a D2D mobility integrator service ecosystem. An exploratory study with German mobility providers was conducted. Our empirical results show that embeddedness in already existing service ecosystems, in particular, reduces their need to gain market legitimacy and for the legitimacy of the new type of smart cooperation. These lead to a lack of cooperation with D2D mobility integrators.