The article attempts to demonstrate the role of decision-making process in actions for sustainable development implemented as part of environmental protection, which is viewed here in a systemic way. The article presents the definition of a system and its surroundings (environment), and points out that environmental protection can be described in this systemic perspective both in general and specific terms. This makes it possible to indicate the scheme and structure of decision-making process. The article examines the possibility of applying Mazur’s control system for designing a scheme of actions that would be adequate for environmental protection, with emphasis placed on the optimisation stage. The author shows that the system developed by Mazur can be used in the PDCA methodology, which is based on the Deming cycle and included in the ISO 14001 standard. As a result, the potential of the systemic approach to environmental protection is shown and it is explained how to move from this approach to a broader strategy for environmental protection and ultimately, to the implementation of sustainable development goals.