We conducted an umbrella review to synthesise the evidence from systematic reviews and meta-analyses that examined the risk and protective factors for self-harm in young people. We searched six different databases and used the AMSTAR-2 checklist for quality assessment. The importance of each risk and protective factor was determined based on (1) the number of times it was identified by general reviews examining any risk or protective factor, and (2) the effect sizes from meta-analyses. There were 61 systematic reviews included in this review. The most frequently identified risk factors for self-harm in young people included childhood abuse, depression/anxiety, bullying, trauma, psychiatric illnesses, substance use/abuse, parental divorce, poor family relationships, lack of friends, and exposure to self-harm behaviour in others. The risk factors with the strongest evidence for an association with self-harm were behavioural disorders, personality disorders and depression or anxiety. There was a dearth of systematic reviews examining protective factors but good family/friend relationships were most frequently identified. There was also evidence to show that non-suicidal and suicidal self-harm shared many of the same risk factors. Clinicians and other professionals who work with young people should be particularly cognisant of the psychiatric and adverse life event risk factors as well as the substance use, education-related and individual-level (e.g. being LGB) risk factors for self-harm. Knowledge of risk factors for self-harm can potentially be used to inform the design and implementation of prevention measures and further research is needed on the protective factors for self-harm.