Protected areas play a crucial role in biodiversity conservation worldwide, but often neglect the involvement of local communities. This study presents a participatory planning methodology for promoting social and economic development in protected areas, using Cotopaxi National Park (PNC) in Ecuador as a case study. The PNC represents an appropriate case study due to its diverse ecosystems and challenges related to grazing activities. The proposed methodology integrates a qualitative approach with the Social Network Analysis (SNA) and the Analytic Network Process (ANP) to design a sustainable management approach. Firstly, the SNA maps the stakeholder network, identifying key actors and their relationships. Secondly, interviews with influential stakeholders provide insights into their perceptions of influence, relationships, and strategies to enhance grazing activities. Thirdly, the ANP is used to analyze and prioritize management strategies. Finally, a novel sensitivity analysis was made to validate the results. The promotion of new opportunities for productive projects and alternative sources of income was the best-rated strategy for sustainable grazing. The proposed methodology can facilitate and improve the co-management of the protected areas and their governance. It allows the integration of environmental conservation objectives with the main concerns of the stakeholders, promoting social and economic development. This study confirms that stakeholders have different interests, sensitivities, and ways of understanding sustainability; thus, improving stakeholder communication and the involvement of additional actors, such as NGOs and government agencies, is crucial. The proposed integrated approach can be adapted to any participatory decision-making process related to the conservation of protected natural areas.