In recent years, we have witnessed the emergence of the Internet of Things (IoT) paradigm as means of allowing for connectivity, interaction, and integration of smart objects, which collaborate with each other to achieve common goals. The characteristics of IoT have challenged Software Engineering, including how to successfully architect complex systems while meeting business goals and satisfying important quality attributes. The use of software architectural styles provides a solid foundation for mitigating risks arisen from the complexity of these systems. In this paper, we propose an architectural style for IoT systems in conformance with the IoT conceptual model defined by the ISO/IEC 30141 International Standard. We specify the style by using the SysADL language in terms of the description of its architectural elements, structure, behavior, and constraints. We validated the style through the architectural design of a real-world IoT system and evaluated its use through an exploratory experiment.