Assessing management effectiveness in protected areas is a fundamental instrument to achieve socio-biodiversity protection goals. This study aimed to analyze the management effectiveness of Cunhambebe State Park (from now on, “PEC”) in the State of Rio de Janeiro in Brazil, from the perception of stakeholders and the multi-temporal analysis of land use and land cover between 1998 and 2018. We used the Rapid Assessment and Prioritization of Protected Area Management method for a participatory approach. Seventy-two indicators were used and applied to assess the perception of stakeholders related to the Advisory Council. The management effectiveness of PEC was classified as moderately satisfactory (63.41%). Indicators of “Legal security”, “Vulnerability”, “Site design and planning” and “Financial resources” revealed the weaknesses and threats of management and what should be the priority projects for better effectiveness. Through the multi-temporal analysis, we identified that the advances of pasture and urban areas are the highest pressures and threats, as perceived by stakeholders. In our case study, we provide evidence of actions that must be performed by the PEC management team. These actions must consider the weaknesses and threats presented by the SWOT analysis. Finally, we recommend some political and management measures: 1) Financial resources for the land regularization of areas overlapping with PEC, 2) Guidelines about PEC areas must be included in the Master Plans of municipalities that cover PEC limits, 3) Technical assistance to improve land management, and 4) Strengthen environmental education initiatives at all school levels.