Introduction: Endoscopic retrograde cholangiopancreatography (ERCP) is a key therapeutic procedure for biliary and pancreatic disease but relies on fluoroscopy, exposing patients and staff to ionising radiation. Radiation practices during ERCP are variably applied and rarely standardised. This study evaluated the impact and sustainability of a structured radiation reduction protocol within a high-volume Australian ERCP service. Methods: A combined retrospective and prospective cohort study was conducted in a tertiary ERCP unit. Radiation metrics were compared across pre and post standardised protocol implementation. The intervention comprised targeted education, predefined low-dose fluoroscopy settings, optimisation of C-arm positioning, and standardised communication between endoscopists and radiographers. ERCPs were performed using under-couch C-arm fluoroscopy. Radiation dose metrics and fluoroscopy time were analysed, adjusting for procedural complexity, trainee involvement, and fluoroscopy unit variables. A multidisciplinary staff survey assessed protocol adherence and sustainability. Results: Protocol implementation resulted in reduced fluoroscopy time and radiation dose without compromising procedural success or patient safety. Radiation exposure correlated with procedural complexity, trainee participation, and fluoroscopy unit characteristics. Improved endoscopist–radiographer communication was identified as a key contributor to both initial dose reduction and sustained practice change. Survey responses demonstrated high protocol acceptance and ongoing awareness of radiation safety principles. Conclusion: A standardised radiation reduction protocol achieved durable reductions in radiation exposure during ERCP. Embedding behavioural strategies and multidisciplinary communication into routine workflow enables sustainable practice change and supports safer ERCP without adverse clinical impact.