Despite being commonly recommended, the impact of anticancer drugs (ACDs) on patient-important outcomes beyond survival for advanced hepatobiliary cancers (HBCs) may not have been sufficiently assessed. We aim to identify and map the evidence regarding ACDs versus best supportive care (BSC) for advanced HBCs, considering patient-centered outcomes. Methods: In this mapping review, we included systematic reviews, randomized controlled trials, quasi-experimental, and observational studies comparing ACDs (chemotherapy, immunotherapy, biological/targeted therapy) versus BSC for advanced HBCs. We searched MEDLINE (PubMed), EMBASE (Ovid), Cochrane Library, Epistemonikos, PROSPERO and clinicaltrials.gov for eligible studies. Two reviewers performed the screening and data extraction processes. We developed evidence maps for each type of cancer. Results: We included 87 studies (60 for advanced liver cancer and 27 for gallbladder or bile duct cancers). Most of the evidence favored ACDs for survival outcomes, and BSC for toxicity. We identified several evidence gaps for non-survival outcomes, including quality of life or quality of end-of-life care. Discussion: Patient-important outcomes beyond survival in advanced HBCs are insufficiently assessed by the available evidence. Future studies need to address these gaps to better inform decision-making processes.