The American Joint Committee on Cancer (AJCC) Precision Medicine Core recently established criteria to evaluate prediction models for incorporation into staging. All previously developed models for localized prostate cancer were excluded from the AJCC 8th edition, primarily because endpoints other than survival were used, and staging was devised through expert opinion. We therefore sought to develop the first AJCC compliant staging system for use in localized prostate cancer. Eligible patients had T1-4N0-1M0 prostate cancer treated between 1992-2013 with radical prostatectomy (RP) or radiotherapy (either external beam (EBRT) and/or brachytherapy with or without androgen deprivation therapy (ADT)). Over 50 centers provided data, including centers in the USA, Canada, and Europe, and across academic, community, and Veterans Affairs medical centers. Patients with M1 disease or PSA>200 ng/ml, and those with preoperative ADT were excluded. The final cohort was randomly split into training and validation sets. An a priori statistical plan was utilized, and statisticians were blinded to the validation cohort until a locked training model was developed. The primary endpoint was prostate cancer-specific mortality (PCSM) treating non-cancer death as a competing-risk. Model discrimination (C-index), calibration, and overall performance (Integrated Brier Score R-squared (IBSR2)) were assessed at 3-, 5-, 10- and 15-years with 10-year results reported below. A total 19,684 men were included, of which 12,421 were treated with RP, 5942 with EBRT, and 1321 with brachytherapy (+/-EBRT). Median follow-up was 72 months (range, 1-289 months), and 4078 were followed for at least 10 years. Novel cut points and groupings were identified that are not currently used in existing prognostic systems, including age, PSA, and percent positive cores. In the new score model, nine tiers were identified (Stage Ia-c, IIa-c, and IIIa-c), and predicted 10-year PCSM ranged from 0.3% to 40%. In the validation set, 10-year discrimination for the new system (C-index 0.796) were superior to the AJCC 8th edition (0.757); overall performance (IBSR2 0.048) was also improved over AJCC 8th edition (IBSR2 0.035). The new staging system was also superior to AJCC 8th edition across primary treatment modality (surgery, EBRT, brachytherapy), age, and race. Using a large, diverse international cohort treated with standard curative treatment options with long term follow up, we have developed and validated the first AJCC compliant clinical staging system for prostate cancer that is superior in each metric to the current AJCC 8th edition and is ready for AJCC committee evaluation.