Background: Jordan’s population of older adults is growing due to improved health care and lifestyle, but the country has limited mental health care resources, causing challenges for the health care system. Reminiscence is a point of nursing intervention and a way for psychiatric nurses to help people improve their mental health by expanding their personal boundaries (self-transcendence). Aims: The study aimed to examine the mediating effects of self-transcendence on the relationship between reminiscence functions and death anxiety in a sample of Jordanian older adults. Psychiatric nurses can refine reminiscence therapy by targeting aspects of self-transcendence to reduce death anxiety. Methods: An online cross-sectional survey was employed to collect the data. A total of 319 older adults participated in the study. The sample was recruited using convenience and snowball sampling strategies through social media and personal contacts. Results: The reminiscence function of “Bitterness Revival,” gender, the presence of a life-threatening disease, a history of psychiatric disorder, and the work sector were statistically significant predictors of death anxiety. This model accounts for 24% of the death anxiety score ( F = 7.789, p < .001). Reminiscence functions 1, 2, and 5 predicted self-transcendence. This model explained 25% of the variance in the self-transcendence score ( F = 6.548, p < .001). Self-transcendence exerts a positive, partial mediating effect between “Bitterness Revival” and death anxiety, controlling for other covariates in the death anxiety model ( p = .016). Conclusions: The study is informative for understanding the role of self-transcendence in buffering death anxiety, notwithstanding “Bitterness Revival” reminiscences. This knowledge reveals practical implications for psychiatric nurses about the importance of developing reminiscence interventions to promote self-transcendence and ease death anxiety.