The 2030 Agenda, through its Sustainable Development Goals (SDGs), establishes a new global paradigm for promoting a shared and sustainable model of economic, social, and environmental development. This transformation calls for tools and methodologies capable of systematically embedding the sustainability paradigm into governance processes. In this context, Strategic Environmental Assessment (SEA) serves as a potentially powerful instrument to actively steer decision-making towards sustainable development and to translate it into practice. This paper explores the potential of SEA as an operational tool for integrating sustainability into spatial and territorial planning. Using the Tepilora Regional Natural Park Plan in Sardinia as a pilot project, the paper presents a practical application of a SEA model fully integrated into the decision-making process. The model promotes sustainable territorial development by combining environmental protection, landscape enhancement, and local sustainable development objectives. It is structured around the Logical Framework Approach (LFA), ensuring a coherent and goal-oriented planning process integrated with the assessment framework. The findings highlight the key stages of the strategic process in which the sustainability paradigm, interpreted and contextualised through the Regional Strategy for Sustainable Development (RSSD), is incorporated from the outset of plan formulation. The integration occurs in both strategic and design terms, influencing the definition of objectives, the evaluation of alternatives, and the identification of actions. The proposed methodology enhances consistency, traceability, and effectiveness, while enabling verifiability and adaptability. It proves replicable across diverse institutional and territorial contexts, contributing to the development of a proactive SEA process that is fully integrated with the 2030 Agenda, its regional sustainability frameworks, and the context-specific needs that emerged during the planning process.