This study examines how tourism expansion reshapes environmental governance and justice in the Gunung Sewu Karst Landscape, Gunungkidul. It aims to explain how layered legal regimes operate in practice and why regulatory density can coexist with socio-ecological vulnerability. A qualitative socio-legal case-study design was applied to legal instruments, policy documents, official tourism statistics, UNESCO materials, scholarly publications, and credible public reports published between 2014 and August 2026. The documents were organised in an analytical matrix and thematically coded using an environmental-governance framework and three dimensions of environmental justice: distributive, procedural, and recognition justice. The findings indicate that tourism growth strengthens development incentives and the commodification of space, while karst protection remains institutionally fragmented. Economic benefits are tangible, but ecological and social risks may be unevenly distributed and persist across generations. Participation may consequently function as procedural consultation rather than meaningful influence over development limits, while local ecological knowledge remains insufficiently recognised. The article introduces regulated deviation to describe a process in which development proceeds through formally valid administrative mechanisms but cumulatively diverges from the ecological purposes and substantive-justice objectives of environmental law. The study concludes that integrated, protection-first governance, transparent environmental information, meaningful participation, and cumulative-impact assessment are essential for aligning tourism development with socio-ecological justice.