Anger is common problem for which counselling/psychotherapy clients seek help, and is typically regarded as an invidious negative emotion to be ameliorated. However, it may be possible to reframe anger as a moral emotion, arising in response to perceived transgressions, thereby endowing it with meaning. In that respect, the current paper offers a ‘bird’s eye’ systematic review of empirical research on anger as a moral emotion (i.e., one focusing broadly on the terrain as a whole, rather than on specific areas). Three databases were reviewed from the start of their records to January 2019. Eligibility criteria included empirical research, published in English in peer-reviewed journals, on anger specifically as a moral emotion. 175 papers met the criteria, and fell into four broad classes of study: survey-based; experimental; physiological; and qualitative. In reviewing the articles, this paper pays particular attention to: how/whether anger can be differentiated from other moral emotions; antecedent causes and triggers; contextual factors that influence or mitigate anger; and outcomes arising from moral anger. Together, the paper offers a comprehensive overview of current knowledge into this prominent and problematic emotion. The results may be of use to counsellors and psychotherapists helping to address anger issues in their clients.