Background: Biliary complications remain a major source of morbidity after living-donor liver transplantation (LDLT), particularly in recipients with marked donor–recipient duct size disparity. We evaluated the feasibility and short-term clinical performance of an intraoperatively placed biodegradable internal biliary stent in adult LDLT recipients with duct-to-duct mismatch greater than 50%. Methods: This prospective, single-centre pilot study enrolled 12 consecutive adult LDLT recipients between August 2024 and August 2025. Eligibility required primary LDLT, duct-to-duct biliary reconstruction, and intraoperative confirmation of marked duct mismatch, defined as a donor duct diameter more than 50% smaller than the recipient duct diameter. A biodegradable Archimedes® stent with an 11-week degradation profile was placed entirely within the bile duct across the anastomosis and secured with a 6-0 polydioxanone suture. Outcomes were compared with a frequency-matched historical cohort of 12 adult LDLT recipients transplanted between 2018 and 2023 without stent placement. Matching variables were right-lobe graft use, recipient age band, mismatch category, and biliary reconstruction complexity. The primary endpoint was technical feasibility. Secondary endpoints included anastomotic stricture, bile leak, biliary cast material, cholangitis, endoscopic retrograde cholangiopancreatography (ERCP) requirement, stent migration, and graft loss through 12 months. Results: Technical success was achieved in all 12 stented recipients (100%). Median recipient age was 52 years (interquartile range [IQR], 42–60), and median duct mismatch was 65% (IQR, 58–72). No anastomotic strictures occurred in the stented cohort at 12 months, compared with 5/12 (41.7%) in historical controls (p = 0.037, two-sided Fisher’s exact test). One bile leak (8.3%) resolved with drainage alone. Biliary cast material occurred in 2/12 recipients (16.7%); one required ERCP and one resolved without intervention. ERCP was required in 1/12 stented recipients (8.3%) versus 6/12 controls (50.0%; p = 0.069). No stent migration, cholangitis, pancreatitis, or graft loss occurred in the stented cohort. Conclusions: In adult LDLT recipients with marked duct mismatch, biodegradable internal biliary stenting was technically feasible and demonstrated an acceptable safety profile. Compared with a frequency-matched historical cohort, stented recipients had fewer anastomotic strictures and numerically fewer ERCPs, although comparative inference remains limited by the pilot design and small sample size. Prospective multicentre evaluation is warranted.