This article describes a four-phase methodology for the implementation of integrated management systems in accordance with ISO 9001, ISO 14001 and ISO 45001 standards with the purpose of serving as a guide for micro and small companies. The design of the implementation methodology was developed in 4 stages: collection of information from consulting companies, design of the implementation methodology, development of a management toolbox, and validation through expert judgment. This implementation methodology was validated through expert judgment, and its application was also carried out in an industrial company, obtaining improvements in the performance indicators of quality, environment, safety and health at work. The results show a box of management tools that includes the diagnosis; design and implementation; audit and management review; and certification for the application of quality management systems. It is concluded that the methodology is a viable alternative to be used by micro and small companies, as well as by professionals and students interested in management systems.