Objective To construct a nomogram for predicting the overall survival rate of patients with gallbladder cancer with positive regional lymph nodes (LNs). Methods Data of 1413 patients diagnosed with gallbladder cancer with regional LN metastases from 2000 to 2022 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute in the United States. The patients were randomly divided into a training set and a validation set at a ratio of 7:3. The Cox proportional hazards regression model was used to explore the independent risk factors affecting the survival of patients and construct a nomogram. The receiver operating characteristic (ROC) curve, calibration curve, and clinical decision curve were drawn to evaluate the predictive ability of the model. Results Multivariate Cox analysis showed that age, T stage, M stage, grade, surgery, radiotherapy, and chemotherapy were independent risk factors affecting the overall survival rate of patients with gallbladder cancer with positive regional LNs (P<0.05). These factors were all included in the nomogram to construct the prediction model. The areas under the ROC curves for 6 months, 1 year, and 3 years in the training set were respectively 0.849, 0.825 and 0.821; those in the validation set were respectively 0.826, 0.828 and 0.795. The calibration curves showed good calibration in both the training set and the validation set. The clinical decision curve showed high clinical application value. Conclusion The constructed nomogram model has good predictive ability and can help clinicians predict the overall survival of patients with gallbladder cancer with positive regional LNs, facilitating individualized treatment.