(1) Background: Treatment of male stress incontinence in patients with prostate cancer treated with radical prostatectomy and adjuvant pelvic radiation is a therapeutic challenge. The efficacy and safety of the adjustable trans-obturator male system (ATOMS) in these patients is not well established, despite the general belief that outcomes are worse than in patients without radiation. (2) Methods: Retrospective multicenter study evaluating patients treated with silicone-covered scrotal port (SSP) ATOMS implant after radical prostatectomy and radiotherapy in nine different institutions between 2016 and 2022. The primary endpoint was dry patient rate, defined as pad-test ≤ 20 mL/day. The secondary endpoints were complication rate (defined using Clavien-Dindo classification), device removal and self-perceived satisfaction using the Patient Global Impression of Improvement (PGI-I) scale. Wilcoxon rank-sum test, Fisher's exact test and logistic regression were performed using stepwise method with a 0.15 entry and 0.1 stay criteria. (3) Results: 223 patients fulfilled the criteria for inclusion and 12 (5.4%) received salvage prostatectomy after radiation and 27 (12.1%) previous devices for stress incontinence. After ATOMS adjustment, 95 patients (42.6%) were dry and 36 (16.1%) had complications of any grade (grade I, n = 20; grade II, n = 11; grade III, n = 5) during the first 3 months postoperatively. At a mean of 36 ± 21 months follow-up, the device was explanted in 26 (11.7%) patients. Regarding self-perceived satisfaction with the implant, 105 of 125 patients (84%) considered themselves satisfied (PGI-I 1 to 3). In the univariate analysis, dryness was associated to younger age (p = 0.06), primary prostatectomy (p = 0.08), no previous incontinence surgery (p = 0.02), absence of overactive bladder symptoms (p = 0.04), absence of bladder neck stricture (p = 0.001), no need of surgical revision (p = 0.008) and lower baseline incontinence severity (p = 0.0003). Multivariate analysis identified absence of surgical revision (p = 0.018), absence of bladder neck stricture (p = 0.05), primary prostatectomy (p = 0.07) and lower baseline incontinence severity (p < 0.0001) were independent predictors of dryness. A logistic regression model was proposed and internally validated. (4) Conclusions: ATOMS is an efficacious and safe alternative to treat male incontinence after radical prostatectomy and adjuvant radiotherapy. Factors predictive of dryness are identified in this complex scenario to allow for better patient selection.