Corrective osteotomies are the indicated treatment for complex forearm malunions. The use of 3D computer-assisted preoperative planning offers significant advantages, such as improved comprehension of the multiplanar deformity and high accuracy. However, the clinical application of computer-assisted preoperative planning methods is limited due to the considerable time, effort, and expertise required. This emphasizes the necessity for a tool that can generate clinically feasible osteotomy plans, complying with patient-specific anatomical reconstruction goals. To address this challenge, this research developed an automatic planning tool for corrective osteotomies of radius malunions, requiring minimal user interaction. By automatically registering the pathological and contralateral bone models, the tool provides insight into the degree and nature of the deformity. An Evolutionary Algorithm is implemented to optimize patient-specific osteotomy plans by minimizing bone protrusion near the osteotomy plane. The automatic planning tool yields patient-specific osteotomy plans including the osteotomy plane location and orientation, as well as the required reduction of the distal part after the osteotomy cut. These plans ensure accurate alignment of both the proximal and distal radial joint surfaces. The developed tool was validated on 15 patient cases. The osteotomy plans generated by the automatic tool were compared to those planned manually in the past. Objective validation, based on residual alignment errors of the entire radius bone, often favored the manual planning approach. However, the automatic tool consistently provided osteotomy plans with more accurate alignment of the distal joint surface. Additionally, a blinded qualitative validation was conducted with a highly experienced orthopedic surgeon, who rated all osteotomy plans on a scale of 1 to 10. The results indicated that the automatic tool is not yet capable of generating osteotomy plans with feasibility scores equivalent to manual planning. However, the feasibility scores differed by only one point on most patient cases. The main areas that require improvement to consistently produce clinically feasible osteotomy plans include the incorporation of osteosynthesis plate fixation, consideration of the relationship with the ulna, and the option for double-cut osteotomies. In conclusion, the developed tool is capable of generating clinically feasible osteotomy plans, serving as a valuable starting point for patient-specific plans that can be further refined manually.