Self-compassion has been implicated in the aetiology and course of mental health with evidence suggesting an association between greater self-compassion and lower emotional distress. However, our understanding of the nature and extent of the relationship between self-compassion and self-harm (self-injury regardless of suicidal intent) or suicidal ideation remains unclear. This review, therefore, aimed to critically evaluate the extant literature investigating this relationship. To do so, a systematic search, including terms synonymous with self-compassion, was conducted on three main psychological and medical databases (Web of Science, PsycINFO, and Medline).Only studies investigating self-compassion or self-forgiveness and self-harm or suicidal ideation were found to be relevant to the review. Eighteen studies were included in the final narrative synthesis. Heterogeneity of studies was high, and the majority of studies were quantitative and cross-sectional (n = 16) in design. All studies reported significant associations between higher levels of self-forgiveness or self-compassion and lower levels of self-harm or suicidal ideation. Several studies suggested that self-compassion or self-forgiveness may weaken the relationship between negative life events and self-harm. In conclusion, this review highlights the potential importance of self-compassion in the aetiology of suicidal thoughts and self-harm. We discuss the clinical and research implications.