Incorporating sustainability principles into Industry 4.0 initiatives not only promotes eco-friendly innovation and operational effectiveness in industrial processes but also addresses pressing sustainability challenges. Industry 4.0 technologies enable companies to improve flexibility, efficiency, and cost savings while also tackling sustainability issues. This paper focuses on the development of a monitoring system for an injection machine utilizing the Open Platform Communications Unified Architecture (OPC UA) protocol. This modernization effort aims to align the IMI1300S machine, built in 1973, with the principles of Industry 4.0. This transformation enables real-time monitoring and analysis of the injection machine’s operational and produc-tion data. Continuous data analysis enables the evaluation of production ef-ficiency and the generation of new recommendations for process optimiza-tion, including, for example, the reduction of the injection cycle time, lower-ing production costs. The proposed system consists of two complementary modules: an electronic module for acquiring sensor data from the injection process and a software module for processing and storing the data. The elec-tronic module continuously transmits data to the software module, which uti-lizes the OPC UA protocol to structure and store it in a server-hosted data-base. This data is then accessible for analysis by any device with an OPC UA client, or directly from the database. The tests conducted in an industrial en-vironment enabled the validation of the system in terms of its operability and applicability.