Purpose: The purpose of this study was to evaluate the clinical and audiological outcomes in long-term cochlear implant (CI) users, focusing on hearing performance and device failures. Methods: A retrospective study was conducted on patients who underwent CI surgery, with a minimum follow-up of 10 years. Device survival was analyzed using Kaplan–Meier curves, and failure rates were classified as device failure explants or medical-related explants. The time to revision and causes of reimplantation were assessed. Statistical analyses included Pearson correlation for audiological outcomes, Student’s t-test for group comparisons, and the log-rank test for survival comparisons among implant brands. Results: In this study, data from a total of 211 CIs were collected. Fourteen major postoperative complications were reported in this series, resulting in a global major complication rate of 6.6%: 5.2% due to hard failure and 1.4% due to medical problems and soft failure. The revision rate was 4.1% for the children’s group and 10% for the adult group. The overall device survival rates were more than 96% at 10 years and 91% at 20 years. The median postoperative follow-up was 16.3 years. Moreover, a highly significant correlation was observed (r = 0.669, p < 0.0001) between pure tone average (PTA) thresholds at implant activation and those at the last follow-up, as analyzed using Pearson’s correlation coefficient. Conclusions: The CI is a lifelong device; however, the technology is constantly evolving. Therefore, careful patient counseling (or counseling of parents in the case of pediatric patients) is necessary. The device may wear out over time, requiring revision surgery. These data are essential for audiologists and ENT specialists when selecting patients and determining surgical indications.