While the COVID-19 pandemic has affected all types of people, older adults have been disproportionately affected. Therefore, during this period we developed an indoor program inspired by art and natural elements (plant essential oils [EOs]) intended to create a relaxing effect akin to a forest atmosphere to enhance their psychophysiological health. There are for 30 Taiwanese older adults (range, 59-79 years) participated in the study. We combined art activity (still-life painting of vegetables) with breathing Pseudotsuga menziesii and Lavandula angustifolia EOs during a 100-minute experiment involving still-life painting and the inhalation of 2.5% diffused EOs. The research shows physiological measures (heart rate, normalized low-frequency heart oscillations, ratio of low- to high-frequency heart oscillations, high-beta waves, and gamma waves) decreased;correspondingly, an increased standard deviation of normal-to-normal intervals, normalized high-frequency heart oscillations, and high-alpha waves were observed, indicating relaxation physiological state. Subjective psychological assessments using the State-Trait Anxiety Inventory–Stateyielded lower post-test scores, further supporting relaxation effects. The psychophysiological data from this study provide important scientific evidence for the physical and mental health benefits of indoor nature-based activity programs for older adults, thereby improving their quality of life.