OBJECTIVE: To evaluate the effectiveness of preventive nursing interventions in reducing treatment-related complications among patients with ovarian cancer. SETTING: Retrospective cohort study. PARTICIPANTS: A total of 251 female patients with ovarian cancer were included. They were assigned to either a control group (n=134), receiving standard nursing care, or an observation group (n=117), receiving additional preventive nursing interventions. INTERVENTIONS: The control group received standard nursing care, including routine health education, pharmacological symptom control, and vital sign monitoring. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was the incidence of treatment-related complications. Secondary outcomes included the severity of nausea and vomiting, quality of life, psychological condition, and nursing satisfaction. RESULTS: The observation group demonstrated a significantly lower incidence of treatment-related complications compared to the control group (P=0.001). Notable reductions in nausea, vomiting, and neuropathy were observed (P=0.015, P=0.035). Both groups showed improvements in psychological conditions post-intervention (P<0.001); however, improvements were more significant in the observation group for depression and quality of life (P=0.004, P=0.007). Nursing satisfaction was also significantly higher in the observation group (P<0.0001). Multivariate logistic regression revealed that preventive nursing interventions significantly reduced complication risks (OR=0.391, 95% CI: 0.228–0.670, P =0.001), and treatment with carboplatin and paclitaxel was significantly related to increased complication risks. CONCLUSION: Preventive nursing interventions effectively reduce treatment-related complications and enhance clinical and psychological outcomes in patients undergoing ovarian cancer chemotherapy. These findings underscore the importance of personalized, proactive nursing care in oncology settings.