Steel reinforcement is one of the most important materials used in the construction industry. This research optimizes reinforcement bar fabrication by integrating Building Information Modeling (BIM) with visual programming in Dynamo. On-site rebar cutting and bending generate significant material waste, increasing costs and environmental impact. To address this, an intelligent Dynamo script was developed to extract detailed 3D rebar and 4D scheduling data from BIM models. The script optimizes material usage by specifying cut-off lengths to improve reuse and minimize waste. Validation through two real-world case studies demonstrated the method’s significant potential. Effectiveness was assessed using benchmarks comparing the number of bars saved, waste reduced, and overall cost savings. The study confirms that optimized fabrication significantly cuts waste and cost. Its effectiveness, however, varies with rebar type and structural component, with the most significant gains observed in medium-length bars and pile caps. By offering a novel tool for sustainable construction, this research advances BIM-enabled reinforcement design and material optimization.