Environmental sustainability has become a major concern in architecture and interior design due to the growing challenges of climate change, the depletion of natural resources, and increasing energy consumption. In this context, environmental legislation plays a significant role in directing design practices toward balancing aesthetic and functional requirements with environmental considerations, thereby supporting the development of more sustainable and resource-efficient buildings and interior spaces. Environmental legislation establishes standards that must be considered during the building design process, including energy and water efficiency, indoor air quality, waste management, and the selection of environmentally friendly construction materials. These regulations also help reduce the negative environmental impacts of urban development and encourage architects and designers to adopt innovative solutions that minimize resource consumption and harmful emissions. In interior design, the influence of environmental legislation is reflected in the selection of materials and finishes, the use of natural lighting, the provision of adequate ventilation, and the integration of energy-efficient systems. For example, selecting low-emission materials can improve indoor air quality, while carefully planned interior spaces can reduce dependence on artificial lighting and continuous cooling. These measures provide environmental, economic, and health benefits for building occupants. Environmental regulations also encourage the adoption of sustainable design principles, including material reuse and recycling, waste reduction, and flexibility in the use of interior spaces. These principles are particularly important in educational institutions and public buildings, where a healthy and comfortable indoor environment can enhance productivity and improve the user experience. Furthermore, environmental standards can support the development of green buildings through recognized assessment systems and sustainability certification schemes. Despite their importance, implementing environmental legislation may involve several challenges, including the high cost of certain sustainable materials and technologies, limited environmental awareness, a shortage of specialized expertise, and inconsistent enforcement. Addressing these challenges requires stronger cooperation among legislative authorities, engineering institutions, and academic organizations, alongside professional training for designers and greater public awareness of sustainability. In conclusion, environmental legislation is a key factor in advancing sustainable architecture and interior design. Its importance extends beyond regulating construction activities to establishing the designer’s responsibility toward the environment and society. Compliance with environmental requirements, combined with creative solutions and modern technologies, can produce buildings and interior spaces that achieve aesthetic and functional excellence, conserve natural resources, and contribute to a more sustainable future for generations to come.