To analyze the association between the prognostic nutritional index and surgical morbidity in women with gynecologic cancers. This is a retrospective cohort study of women with ovarian, endometrial, or cervical cancer who underwent surgery between January 2013 and December 2020 at a cancer center. Demographic and clinical data were extracted from electronic medical records. The prognostic nutritional index was calculated during the immediate pre-operative period. Binomial logistic regression was conducted to identify the association of the prognostic nutritional index with the outcome of surgical complications after Clavien-Dindo classification, adjusting for confounding variables. A total of 1000 women were included: 114 (11.4%) were diagnosed with cervical cancer, 551 (55.1%) with ovarian cancer, and 335 (33.5%) with endometrial cancer. Patients with a prognostic nutritional index >40 had a decreased possibility of surgical complications (OR=0.39, 95% CI 0.29 to 0.52); basal blood hemoglobin, volume of surgical bleeding, operative time, and length of hospital stay were also explanatory factors. The prognostic nutritional index has a significant effect on patients with endometrial and cervical cancer, but conversely is not significant in patients with ovarian cancer. The prognostic nutritional index is associated with surgical morbidity in endometrial and cervical cancers and thus can be a useful tool for predicting morbidity and guide pre-operative interventions in patients with gynecological cancers.