Introduction Older adults have one of the highest age‐specific suicide rates in France, and the risk of suicide is higher for those living in nursing homes. The aim of our study was to assess the effectiveness of gatekeeper training for nursing home staff on the knowledge and stigmas towards suicidal crisis and the impact on suicidal behaviour rates. Method A total of 427 nursing or administrative staff from 110 nursing homes received gatekeeper training in the Hauts-de-France French region between September 2016 and June 2018. First, knowledge and stigmas on suicidal crisis were assessed through a pretest and posttest survey. Second, a retrospective survey was conducted to determine suicide behaviour rates before and after training in nursing homes. Then, changes between pre- and posttraining scores and suicide rates were evaluated with a paired samples T test and rate difference calculation (P value of <0.05 was considered statistically significant). Results A total of 315 trainees completed the questionnaires on knowledge and stigmas related to suicidal crisis, and we found a significant difference in the total scores (P < 0.01). Moreover, we found a significant decrease in the incidence of suicide attempts (SAs) after training (P = 0.002), but the incidence of deaths by suicide was not significantly different prior to and after the training course (P = 0.46). Conclusion We highlighted an improvement in knowledge and stigmas after training and a reduction in the rates of SAs with our gatekeeper suicide prevention program. Future research is needed to improve suicide prevention for nursing home residents.