In the context of the studies on FinTech, this empirical research aims to understand the evolution of the FinTechs ecosystem and to strengthen its characterization through the perspectives of socio-technical system theory and service innovation. For this analysis, the case study research methodology was used, in which 11 FinTechs startups that are part of the Portuguese and Brazilian context were considered. Primary data were collected through semi-structured interviews with C-level and startups employees, while secondary data were obtained through reports from large consulting firms and public relations materials from FinTechs startups. The results show the evolution of the FinTechs ecosystem from the perspective of socio-technical system theory and service innovation. For socio-technical system perspective, it was possible to understand the evolution of this ecosystem from the roles of social, technological and organizational actors. Thus, it can be understood how each stakeholder influences the development of FinTechs business, in the creation of new products and services. For service innovation perspective, it was possible to understand the dynamics of the evolution of the FinTechs ecosystem and its results. The academic contribution to service innovation is present during the innovation process of the studied FinTechs, where they were identified as the stakeholders who are part of the ecosystem, impact on the incremental, radical, improvement and recombinative innovations of startups. The contribution to the socio-technical system theory is present during the use of the structure that allows understanding the development of the ecosystem and social, technological and organizational actors. Finally, the contribution to management can be defined as the characterization of the FinTechs ecosystem for the entrepreneurs who work with these startups to better understand the environment in which they are inserted.