<p>As individuals age, they tend to spend more time indoors, underscoring the increasing importance of interior design for healthy aging. Although existing research on this topic is extensive, it lacks integration and consistency, thereby hindering the development of concrete design guidelines. This study employed a scoping review to systematically examine existing literature, clarifying how interior design factors—including indoor environmental quality, layout, and elements—affect the physical, physiological, and mental health of older adults. Following the PRISMA-ScR guidelines, 64 empirical studies published between 2005 and 2024 were analyzed, sourced from Web of Science, Scopus, and PubMed databases. This scoping review highlighted seven key interior design principles that influence older adults’ health: lighting, thermal environment and air quality, spatial layout, barrier-free design, space size, furniture, and relaxation design. The study also revealed evolving research trends through VOSviewer keyword analysis. Across the reviewed studies, differences in design recommendations appeared to reflect regional contexts and varying degrees of frailty among older adults. However, research on physiological responses to various interior design factors remains relatively limited. Future studies could benefit from integrating smart sensing technologies and interdisciplinary approaches to deepen the understanding of how interior design influences the health of older adults.</p>