The reengineering of systems into a microservice-based architecture can be seen as an implementation of a service-oriented architecture (SOA). However, the deployment of SOA into an enterprise is a challenging task, as it may involve the modernization of mission-critical systems with high technical debt and high maintenance costs. To this end, a process is required to provide an appropriate set of steps and techniques that minimize risks and at the same time ensure the quality of the systems during the migration process. Thus, this work presents the Service-oriented Process for Reengineering and DevOps—SPReaD, an instantiation of the mainstream SOA methodology focusing on the reengineering of legacy systems integrating DevOps aspects for developing microservices systems. This process has been defined during a real software reengineering project of legacy systems from a Brazilian State Department of Taxation. The results obtained include a substantial improvement in the quality of the main taxation system used by the state, including not only code-related metrics but also performance improvements of the services offered, and a change in the methodology adopted by the software development team.