Current literature shows that interaction with urban greenery can have a wide range of positive health outcomes. Targeted nature-based programs, such as therapeutic horticulture, have been shown to result in multiple health benefits for older adults residing in temperate environments, but much less research has been carried out on populations with different phenotypes, such as older Asian adults in the tropics. The current study investigated the effects of a 24-session therapeutic horticulture program on 47 older participants in Singapore, with an experimental pretest posttest design. We found that participants maintained healthy sleep patterns and psychological health, as well as showed reduced anxiety and improved cognitive functioning (p < 0.05). In addition, they reported an increase in mean happiness score after each session. This study provides new evidence using a comprehensive set of indicators across the affective, cognitive, functional, psychosocial and physical domains, supporting current literature on the benefits of nature programs, with a novel focus on tropical environments. It provides evidence that the nature-based intervention has the potential to be translated to programs to benefit older adults in the tropics.