Purpose <p>This systematic review investigates the effectiveness of online self-compassion-based interventions and their impact on the outcomes of cancer patients.</p> Methods <p>A comprehensive search was carried out in the Web of Science Core Collection, Cochrane Library, CINAHL, PubMed, ScienceDirect, Scopus, Ovid, and SpringerLink databases without any year limitation until January 01, 2026. Cochrane and PRISMA guidelines were used for systematic review and reporting. RoB2 and Joanna Briggs Institute guidelines were utilized to assess the risk of bias.</p> Results <p>Eight studies included in the systematic review were conducted between 2017 and 2025 in Australia, the USA, the Netherlands, China, and Türkiye. The self-compassion interventions applied in the studies included mindful self-compassion, self-compassion-focused writing, compassion mind training, and kindness interventions. Online self-compassion-based interventions have been found to increase patients’ levels of self-compassion, mindfulness, body image appreciation, well-being, self-acceptance, posttraumatic growth, and positive affect while reduce their levels of self-criticism, social isolation, anxiety, stress, and depression, body image distress.</p> Conclusions <p>Studies have shown the positive effects of self-compassion-based interventions on patient outcomes. A sensitivity analysis that included only randomized controlled trials demonstrated robustness in all outcomes except anxiety; however, some research results were obtained from a single randomized controlled trial. Since some study results were derived solely from quasi-experimental studies, they were not included in the analysis. Therefore, more randomized controlled research is required to integrate these interventions into clinical patient care. Online self-compassion interventions can contribute to the planning of holistic nursing interventions for patient outcomes.</p>