Patient violence in emergency departments (EDs) may be prevented with proactive mitigation measures targeting potentially violent patients. We aimed to evaluate the effects of two interventions guided by a validated risk-assessment tool. A prospective interventional study was conducted among patients ≥10 years who visited two EDs in Michigan, USA, from October 2022 to August 2023. During triage, the ED nurses completed the Aggressive Behavior Risk Assessment Tool for EDs (ABRAT-ED) to identify high-risk patients. Following the baseline observational period, interventions were implemented stepwise for the high-risk patients: phase 1 period with signage posting and phase 2 period with a proactive Behavioral Emergency Response Team (BERT) huddle added to the signage posting. Before ED disposition, any violent events and their severities were documented. The data were retrieved retrospectively after the study was completed. Of 77,424 evaluable patients, 546 had ≥1 violent event. The violent event rates were 0.93%, 0.68%, and 0.62% for baseline, phase 1, and phase 2, respectively. The relative risk of violent events for phase 1 compared to the baseline was 0.73 (95% confidence interval [CI]: 0.59‒0.90; p=0.003). The relative risk for phase 2 compared to phase 1 was 0.92 (95% CI: 0.76‒1.12; p=0.418). The use of signage posting as a persistent visual cue for high-risk patients identified by ABRAT-ED appears to be effective in reducing the overall violent event rates. However, adding proactive BERT huddle to signage posting showed no significant reduction in the violent event rates compared to signage posting alone.