Introduction: Nurses, who care for patients with various traumas, may also experience post-traumatic stress disorder due to indirect or direct exposure to traumatic situations. This study examined the effectiveness of an Internet-based trauma recovery intervention for Korean nurses. Methods: This randomized controlled trial was conducted with 112 nurses aged 23–40 years who were randomly assigned to the intervention (n = 56) or control group (n = 56) from May 7 to December 20, 2020. Nurses in the intervention group attended eight sessions, and the same intervention was administered to the control group. Repeated measures were collected at pre-test, post-test 1 (immediately after the intervention), and post-test 2 (4 weeks after the intervention). A total of 102 nurses (intervention group: n = 49; control group: n = 53) were completed because 10 nurses dropped out before the first session. Data were analyzed using the χ2 test, Fisher’s exact test, t-test, Mann-Whitney U test, and repeated measures ANOVA (intention-to-treat and per protocol). Results: There were significant changes in functional health, resilience, post-traumatic stress, depressive symptoms, state anxiety, and trait anxiety over time and in the group-by-time interactions (intention-to-treat and per protocol). There was a significant difference in social support in the group-by-time interactions, but there were no significant changes between the two groups or over time (intention-to-treat and per protocol). Conclusion: The Internet-based trauma recovery nursing intervention is effective in clinical and community settings for nurses who cannot participate in fixed-schedule programs due to shift work. This study’s findings are relevant for implementing Internet-based trauma recovery programs for nurses and the general population, including survivors and relatives of patients who suffered from COVID-19. This program will also be very useful for people in other high-stress situations. Nurse leaders should consider different populations and situations when offering effective coping strategies suitable for changing environments.