Background: Biliary tract cancer (BTC) is a fatal disease characterized by molecular heterogeneity, which results in variations in biological behavior. Despite this, the knowledge of pathogenic alterations in the Chinese BTC population using next-generation sequencing (NGS) profiles remains limited. Therefore, we performed a retrospective investigation to assess the predictive significance of DNA damage repair (DDR) mutations in facilitating precision medicine for this disease. Methods: NGS profiling was carried out on resected tissues obtained from Chinese patients diagnosed with advanced BTC. In addition, baseline clinical and genetic characteristics were collected, along with data on their survival outcomes. Results: A total of 68 Chinese patients with BTC who received first-line platinum-containing chemotherapies were enrolled in this study [intrahepatic cholangiocarcinoma (ICC), 33; extrahepatic cholangiocarcinoma (ECC), 13; gallbladder carcinoma (GBC), 22]. Genetic alterations were observed in 67 patients (98.5%), with TP53 (50.0%), KRAS (26.8%), ARID1A (16.2%), and CDKN2A (16.2%) being the most commonly mutated genes. Patients with TP53 mutations demonstrated a trend towards reduced median OS (16.6 vs. 20.1 months, P=0.145). Mutations in DDR genes were identified in 29 (42.6%) of overall patients, primarily involving ATM (11.8%) and BAP1 genes (8.8%), and were significantly associated with longer mPFS (6.4 vs. 4.8 months, P=0.022) and mOS (21.2 vs. 14.3 months, P=0.011) in patients who received first-line platinum-containing chemotherapies. DDR-mutated patients treated with PD-1 blockades showed a tendency towards improved overall survival compared to the DDR-naive group (20.8 vs. 14.3 months, P=0.297). Furthermore, tumor mutational burden (TMB) could be estimated in 63 cases and was significantly higher in those with DDR mutations (P=0.029). Conclusions: Genetic information can aid in identifying a subgroup of BTC patients who may benefit from targeted therapy, this retrospective study demonstrated the predictive significance of DDR mutations for platinum-based chemotherapy efficacy in Chinese patients. Nonetheless, additional research is necessary to explore the potential of DDR mutations in predicting sensitivity to PD-1 blockade.