<p>Pelvic reconstruction after tumor resection remains one of the greatest challenges in orthopaedic oncology because of the pelvis’s complex anatomy, critical load-bearing function, and proximity to major neurovascular and visceral structures. Traditional reconstruction methods, including allografts and standardized modular prostheses, are limited by poor anatomical conformity, mechanical complications, and insufficient long-term stability. This review summarizes the evolution of prosthetic reconstruction for pelvic defects, from standardized implants to modular systems and, more recently, to three-dimensional (3D)-printed personalized prostheses. Using the Enneking classification as a structural framework, we analyze defect-specific design principles for type I (ilium), type II (periacetabular), type III (pubis/ischium), type IV (sacral), and combined defects. Standardized prostheses prioritized basic load-bearing restoration and broad applicability, whereas modular systems improved intraoperative adaptability and introduced preliminary biological fixation concepts. In contrast, 3D-printed personalized prostheses enable a more integrated strategy that combines anatomical matching, biomechanical optimization, and osseointegration through patient-specific geometry, porous interfaces, and tailored fixation pathways. We further propose a triangular decision-making model based on defect region, residual bone stock, and functional demand to guide reconstruction planning. This model helps define priorities in fixation, structural support, and functional restoration across different pelvic regions. For combined defects, reconstruction should emphasize restoration of posterior pelvic stability first, followed by acetabular function and selective anterior ring reconstruction. Nevertheless, 3D-printed personalized prostheses should currently be regarded as a promising patient-specific reconstructive option rather than an established standard-of-care treatment, because their broader application is still limited by insufficient long-term evidence, cost, technical complexity, and manufacturing accessibility. Current challenges include adaptation in pediatric patients, limited long-term evidence, high cost, technical complexity, and the lack of standardized evaluation systems. Future directions include AI-assisted design, bioactive surface modification, and 3D bioprinting, which may shift reconstruction from mechanical replacement toward regenerative repair.</p>