The escalating elderly population has highlighted mental health concerns, especially the impacts post-bereavement. This study investigated depression trajectories post-bereavement and their relation to suicidal thoughts among elderly South Korean males, considering demographic variables. Using data from the 7th to 16th Korea Welfare Panel Study (2012–2021), depression was measured via the CES-D (Center for Epidemiological Studies-Depression) scale, and suicidal thoughts were annually identified. Results revealed two post-bereavement depression trajectories: a predominant “Maintenance Type” (79.4%), showing persistent depression, and a “Decreasing Type” (20.6%), where depression reduced over time. Individuals in the “Maintenance Type”, often living alone, exhibited a higher risk of suicidal ideation. These findings emphasize the need for tailored interventions addressing social isolation and enhanced community support for the elderly to improve mental well-being.