This study explores the socio-environmental implications of the expansion of Madeira International Airport—Cristiano Ronaldo Airport—on the municipality of Machico, a historically significant region on the island’s southeastern coast. As tourism intensifies across Madeira, infrastructure growth presents both opportunities and challenges for sustainable development. The research investigates how increased air connectivity affects local ecosystems, cultural identity, and socio-economic conditions, while also assessing community perceptions and the evolution of tourism dynamics in Machico. A mixed-methods approach was employed, combining semi-structured interviews with local stakeholders, document analysis, and GIS-based spatial mapping of land use. Particular attention was given to the ECOS MACHICO initiative, which integrates environmental protection, heritage preservation, and sustainable tourism planning. Drawing comparisons with similar island contexts such as the Azores and Seychelles, the study identifies best practices and offers context-specific recommendations. Key findings indicate that while the airport expansion has improved accessibility and generated economic opportunities, it has also increased environmental pressure, altered urban dynamics, and deepened dependency on mass tourism. The study advocates for integrated planning approaches that incorporate biodiversity conservation, diversification of tourism products, and robust monitoring frameworks. This case contributes to the growing body of literature on sustainable tourism in insular territories and highlights the need for proactive strategies that balance development and conservation. It offers practical insights for policymakers, urban planners, and tourism stakeholders aiming to navigate infrastructure-led transformations while ensuring long-term ecological and social resilience.