This study aims to develop a nomogram to predict the probability of cancer control at 6 years after salvage radiation therapy (SRT) for patients with recurrent prostate cancer after radical prostatectomy. The nomogram is based on multivariable Cox regression analysis of data from 1,540 patients from multiple institutions. The 6-year progression-free probability was 32% overall, with 48% of patients treated with SRT alone at PSA levels of 0.50 ng/mL or lower disease-free at 6 years. Significant predictors of disease progression included PSA level before SRT, Gleason grade, PSA doubling time, surgical margins, androgen-deprivation therapy (ADT), and lymph node metastasis. The nomogram had a concordance index of 0.69 and was well calibrated. The nomogram is useful for predicting the outcome of SRT and can help guide medical decisions for patients with rising PSA levels.This study aims to develop a nomogram to predict the probability of cancer control at 6 years after salvage radiation therapy (SRT) for patients with recurrent prostate cancer after radical prostatectomy. The nomogram is based on multivariable Cox regression analysis of data from 1,540 patients from multiple institutions. The 6-year progression-free probability was 32% overall, with 48% of patients treated with SRT alone at PSA levels of 0.50 ng/mL or lower disease-free at 6 years. Significant predictors of disease progression included PSA level before SRT, Gleason grade, PSA doubling time, surgical margins, androgen-deprivation therapy (ADT), and lymph node metastasis. The nomogram had a concordance index of 0.69 and was well calibrated. The nomogram is useful for predicting the outcome of SRT and can help guide medical decisions for patients with rising PSA levels.