Background Depressed mood and low life satisfaction are prevalent in older adults. Older adults experience difficulties accessing evidence-based psychological treatments for depression. Reminiscence therapy (RT) is an evidence-based treatment for late life depression. The therapy is usually delivered one-to-one or in groups over several sessions. The therapy could be delivered in a brief online self-guided format. The feasibility and effectiveness of this format is underexplored. This study explored the feasibility and effectiveness of life review therapy when offered as a single-session online self-guided program for improving depression and life satisfaction in older adults. Method Adults aged 65 or over who were living in Australia participated in the study. They completed an online task that involved writing answers to questions about past problem-solving success. They completed measures of depressed mood and life satisfaction before and after this task. Results Of 67 participants (mean age 74.8; SD 5.61, range 65-87), 60 (89.6%) were considered compliant with the task prompts (mean age 74.98; SD 5.7, range 65-87), suggesting that the task was feasible. Mood significantly improved following the reminiscence activity for all participants. Life satisfaction significantly improved for compliant participants only. The practical implications of these findings are discussed. Conclusions Online life review therapy can be an easy, highly accessible and feasible tool to alleviate mood disturbance and improve life satisfaction in older adults.