Active middle ear implants (AMEIs) such as the Vibrant Soundbridge (VSB) offer an effective treatment option for patients with mixed or conductive hearing loss and large air–bone gaps, where conventional hearing rehabilitation often fails. However, postoperative outcomes—particularly speech intelligibility at 65 dB SPL in free-field (WRS_65dB)—show high interindividual variability. This study aimed to develop a predictive model for WRS_65dB based on four clinically relevant parameters: postoperative bone conduction thresholds (BC_PTA4), unaided preoperative maximum speech intelligibility (WRS_max), Vibrogram threshold (VIB_PTA4), and age. Data from 20 patients were analyzed. Spearman’s correlation revealed significant associations between WRS_65dB and postoperative BC_PTA4, preoperative WRS_max, and age. Using a seven-step approach supported by GPT-4o, we developed a sigmoid-transformed linear regression model. The final model included BC_PTA4, WRS_max, and age and achieved an R² of 0.51, r = 0.71, RMSE = 6.18, and MAE = 4.67. Model performance was assessed by means of residual and outlier analysis. This model provides a transparent and clinically applicable tool for preoperative outcome estimation in VSB candidates. Further validation in larger, multicenter cohorts is needed to confirm its generalizability.