Cultural Ecosystem Services (CESs), including recreation, aesthetics, and cultural identity, are vital to socio-ecological resilience but remain difficult to assess due to their intangible and spatially heterogeneous nature. This study presents a spatially explicit framework to evaluate the impacts of land-use and land-cover change (LULCC) on CES in the Alqueva region of southern Portugal—a landscape that is undergoing rapid transformation driven by irrigation expansion and agricultural intensification. Using a combination of geospatial modeling, participatory GIS (PPGIS), stakeholder consultation, and scenario analysis, we assess CES under a 2040 Business-as-Usual trajectory. The preliminary results indicate a progressive decline in key CES, particularly those linked to cultural heritage, recreation, and aesthetic values, due to landscape homogenization and the erosion of traditional Montado systems. Despite this trend, multifunctional landscapes within the current matrix continue to support CES provision, emphasizing the role of sustainable land management in maintaining cultural and ecological functions. Stakeholder feedback reinforces concerns over cultural loss, sense of place, and the weakening of local identity, supporting the integration of CES into spatial planning and ecosystem restoration. This study contributes a replicable, multi-scale methodology that combines qualitative and quantitative approaches, offering policy-relevant insights for aligning land-use dynamics with socio-cultural values and enhancing the role of CES in long-term landscape sustainability strategies.