Healing gardens are green spaces that support the interaction of humans and elements of nature to improve well-being and quality of life. However, little is known about healing garden use and outcomes in African countries. This study aimed to design a healing garden intervention and measure its impact on psychosocial factors and quality of life of residents and care staff within two residential aged care facilities in Lagos, Nigeria. Each facility’s staff completed the psychosocial measurement tools by proxy for participants between ages 60 and 99, with or without dementia, at baseline and three months following interaction with the garden and completed the garden use observational survey to determine the effect on and use of the garden by care staff and residents. Results revealed an improvement in the quality of life and experiences of agitation but no beneficial change in depression among residents with and without dementia. Further, care staff reported a positive benefit of the garden on their work-life experience and the residents’ well-being. This study provides the base for future research on assessing the impact of healing gardens on persons living with dementia in Africa.