Model-based development (MBD) aims at combining modeling languages with model transformers and code generators. Modeling languages, like profiles of the Unified Modeling Language (UML), are increasingly being adopted for specific domains of interest to alleviate the complexity of platforms and express domain concepts effectively. Moreover, system development processes based on automatic model transformations are widely required to improve the productivity and quality of the developed systems. In this paper, we show how MBD principles and automatic model transformations provide the basis for the unified process for embedded systems (UPES) development process and its unified process for system-on-chip (SoC) (UPSoC) subprocess. They have been defined to foster in a systematic and seamless manner a model-based design methodology based on the UML2 and UML profiles for the C/SystemC programming languages, which we developed to improve the current industrial system design flow in the embedded systems and system-on-chip area.Keywords Model-based development (MBD) · Model transformations · Unified modeling language (UML) · SystemC · Embedded system design This work is supported in part by the project Model-driven methodologies and techniques for embedded systems design and analysis based on UML, Abstract State Machines, and SystemC at STMicroelectronics, AST R&I of Agrate