Background Lifeguards may face many life-threatening situations during their careers and may be at increased risk of post-traumatic stress disorder (PTSD). Minimal evidence concerning critical incident management systems in lifeguard organisations exists. Objectives To develop, implement and evaluate an operational system for critical incident management in lifeguard organisations. Methods This retrospective study included data on occupational injury reports from 2013 to 2022 in TrygFonden Surf Lifesaving Denmark. All active lifeguards were invited to evaluate the system and the individual steps using an online questionnaire with three questions rated on a 5-point Likert scale. Primary outcome was a change in the frequency of psychological injury reports after system implementation in 2020. The secondary outcome was the lifeguards' satisfaction with the system. Results After implementation, the average annual number of psychological injury reports increased 6.5-fold from 2 (2013-2019) to 13 (2020-2022), without changes to the number of critical incidents attended by the lifeguards. Sixty-six (33.8%) active lifeguards answered the questionnaire and agreed that follow-up after critical incidents was very important (mean score 4.7/5). Satisfaction with steps 1-2 and 3 of critical incident management among involved lifeguards was high (mean score 4.4/5 and 4.6/5, respectively). The system included an operational workflow diagram and incident report template presented in this study. Conclusions The operational system for critical incident management may improve early recognition of symptoms for the prevention of PTSD. It may be used as a screening and decision tool for referral to a mental health professional.