Non-suicidal self-injury is a complex behaviour, disturbingly prevalent, difficult to treat and with possible adverse outcomes in the long term. Previous research has shown individuals most commonly self-injure to cope with overwhelming negative emotions. Mindfulness has been shown to be associated with emotion regulation, and mindfulness-based interventions have shown effectiveness in a wide range of psychological disorders. This research explored whether lack of mindfulness or problems in mindfulness are involved in self-injury. A non-clinical sample of 263 participants (17–65 years) completed an online survey measuring self-injurious behaviours and mindfulness. Differences in levels of mindfulness between individuals with and without a history of self-injury were investigated. Analysis of variance indicated mindfulness (overall and in terms of specific facets “act with awareness”, “non-judge” and “non-react”) was significantly lower in individuals with a history of self-injury compared to those without. Pairwise comparisons revealed current self-injurers reported significantly lower mindfulness than past self-injurers and non-self-injurers, with medium effect sizes of d = 0.51 and d = 0.77, respectively. In logistic regression, low mindfulness significantly predicted self-injury (B = 0.04, p < .001). These findings have clinical implications, suggesting that mindfulness-based interventions may assist individuals to give up self-injurious behaviours and may be an important part of prevention strategies.