The process of dispersing and distributing functions, powers, and various environment and natural resources from a central location or authority has many implications to a set of procedures in an organised system. This paper presents a case study in the Philippines, specifically in Marikina City in Metro Manila, detailing the systematic examination and analysis of the elements or structure of its decentralisation system as bases for discussion and interpretation of several issues and implications on land use and local environmental planning and management. A site visit was arranged to Marikina City where first hand data and information were obtained from relevant stakeholders in the city. Further, a textual review of Marikina’s current land use and development plan was undertaken. The existing city land use and risk maps were also collected and validated through a windshield survey. Key informant interviews from the heads of city government offices were undertaken to gather in-depth understanding on the implications of decentralisation of their offices. The study found out that there were issues, challenges and opportunities arising from the decentralisation of environmental planning and management in the City of Marikina, Philippines. Although Marikina City has been exhibiting and showcasing good local environmental planning and governance these past several years, some improvements are necessary for the betterment of the City. These warrant policies and actions to solve the problems and to address policy gaps in RA 7160 (The Local Government Code of the Philippines of 1991) in the context of environmental planning and management. The study attempts to enumerate lessons that could be learned on the implications of decentralisation to local environmental planning and management.