Electrical substations play a critical role in energy distribution, where operational failures can lead to service interruptions and increased maintenance costs. The modernization of their monitoring systems is essential, especially in environments that demand reliability and real-time diagnostics. The monitoring of medium-voltage substations traditionally relies on local manual readings and on-site operator interventions, limiting real-time visibility and increasing operational delays. This study presents the development and implementation of a remote monitoring and control system for a medium-voltage substation using Internet of Things (IoT) infrastructure and the Node-RED platform. The objective is to enable real-time supervision and reduce the need for physical presence, improving operational efficiency and safety. The system architecture integrates smart meters, a compact programmable controller (Wago CC100), and industrial communication via the Modbus RTU protocol. The Node-RED environment, combined with FlowFuse Dashboard 2, was used to develop a human–machine interface (HMI) accessible through web browsers. The dashboard displays electrical parameters such as voltage, current, and power, and allows for remote switching operations. System development followed four stages: requirement analysis, communication infrastructure setup, HMI development, and validation testing. Functional tests demonstrated reliable data acquisition and consistent remote control response, validating the system’s performance under simulated operational conditions. The implemented solution highlights the potential of low-code IoT platforms in modernizing legacy electrical infrastructures and aligns with the principles of Industry 4.0 by integrating cyber–physical systems for enhanced supervision, predictive maintenance, and decision-making support in electrical networks.