The contemporary world is undergoing rapid environmental and economic transformations that have prompted a fundamental reassessment of the principles and frameworks governing the design of built environments. As a result, sustainable interior design has become a central approach to reducing environmental impacts and promoting the efficient use of resources. From an academic perspective, sustainability extends beyond the use of environmentally friendly materials to include the assessment of products throughout their life cycles, the reduction of carbon emissions, and the adoption of circular economy strategies through recycling and reuse. The use of locally sourced materials can directly reduce transportation and logistics costs, closely connecting sustainable design with environmental psychology, which examines the reciprocal relationship between people and their built environments. Behavioral research suggests that spaces designed according to carefully considered environmental principles can help reduce stress and promote psychological comfort through balanced visual stimulation and the avoidance of spatial overcrowding that may cause sensory discomfort. Indoor air quality is one of the most important factors that designers must consider. Emissions of volatile organic compounds (VOCs) from certain paints, adhesives, and other finishing materials may negatively affect occupants’ health and comfort. This has encouraged the selection of low-emission, health-conscious materials, alongside the incorporation of indoor plants as natural elements that strengthen connections with nature and create calming, relaxing environments. However, the extent to which plants improve indoor air quality depends on the plant species and the surrounding conditions. Environmental psychology also examines how architectural scale and proportions influence human perception of space. High ceilings may create a sense of spaciousness and encourage creative and exploratory thinking, while some spaces with lower ceilings may promote feelings of enclosure and concentration on detailed tasks, depending on the intended function and the characteristics of their occupants. Likewise, a carefully planned interplay of light and shadow can create a rich visual experience and reduce monotony, provided that a balance is maintained between shared social areas and spaces intended for individual privacy. Smart and adaptive materials offer advanced technical solutions for controlling temperature and lighting, helping reduce the energy required for heating and cooling while supporting environmental sustainability. Achieving a balanced integration of contemporary technology and natural elements remains one of the major challenges facing today's designers, requiring a design language that combines authenticity, innovation, and functional efficiency. In this context, international environmental assessment systems and certifications, such as Leadership in Energy and Environmental Design (LEED) and the WELL Building Standard, provide frameworks for evaluating sustainability, indoor environmental quality, occupant health, and comfort. Adhering to these standards reinforces the importance of considering thermal, acoustic, and visual comfort in interior design. Training designers in sustainable design principles and environmental psychology represents a strategic investment in the future of the built environment. It helps prepare professionals who can understand the relationship between people and places and make design decisions informed by scientific knowledge and environmental responsibility. Continued research into material properties and human behavioral patterns also remains essential to advancing the discipline and strengthening its human-centered approach. In conclusion, integrating sustainable interior design with environmental psychology represents a contemporary approach to creating spaces that are more efficient and comfortable, respond to human psychological and physical needs, and preserve natural resources. Successful interior design goes beyond creating an aesthetically pleasing environment; it involves shaping a balanced setting that respects people, protects the Earth's resources, and supports a better quality of life.