Through a systematic review and meta-analysis of research on individual health and well-being outcomes this paper examines the consequences of witnessing, and thereby being a bystander to, workplace bullying. The review was limited to peer-reviewed primary observational studies with cross-sectional or prospective research design which included findings on outcomes among witnesses to bullying. The review identified 24 relevant studies from 13 countries. Eighty-eight percent of the studies were published from 2010 and onwards. Most studies used cross-sectional single source data from non-probability samples, mainly comprising female respondents from Western countries. Although cross-sectional findings indicated significant associations between witnessing bullying and outcomes such as mental health, job dissatisfaction, and turnover intent, the review show that we need to consider reverse causation, the witness's own exposure to bullying, their proximity and identification with the target, as well as their helping behavior, to understand the true magnitude of the association. Witnessing and being a bystander to bullying is a complex phenomenon and the magnitude of the outcomes relies on a range of third variables and indirect relationships. There is a need for more research to fully understand the consequences of witnessing bullying in the workplace.