Healthcare support workers face challenging situations in their day‐to‐day work but may have minimal training on how to deal with such incidents. Although staff training is often recommended as an essential part of any comprehensive approach for preventing and managing workplace violence, there is paucity of evidence on the content and effectiveness of such training. This study aimed to evaluate the effect of an intervention (communication skills training) to reduce the experience of aggression for healthcare support workers. A two arm, cluster randomised, single‐blinded, controlled trial among healthcare support workers in nongovernmental organisations (NGOs) and District Health Boards (DHBs) in New Zealand was conducted. The trial was conducted across 14 NGOs and DHB in Otago, Southland, and Auckland regions of New Zealand. One hundred and twenty‐seven participants were randomised to one of two groups. Both the intervention (communication skills) and control condition (mindfulness) were group‐based, fully scripted, and structured training interventions that consisted of four once weekly workshops that were facilitated by one of two nonclinical facilitators. Measurements of perceived aggression, psychological well‐being, and distress and communication competence were taken pre‐, post‐, 3 months’ post‐, and 6 months’ postintervention. There was a significant drop in the rate of aggression over time with a mean score and standard deviation of 10.37 (9.169) at baseline dropping to 6.07 (6.923) for the Perception of Patient Aggression Scale‐New Zealand across both intervention and control. Equivalent results were noted with increased psychological well‐being and communication competence and decreased distress with both interventions. This was sustained at 6 months’ follow‐up. However, the between groups effect did not demonstrate a statistically significant difference between the intervention and control groups. Both mindfulness and communication skills training can reduce the experience of aggression reported by healthcare support workers.