Objective: This review presents a recent progress in the application of three-dimensional (3D) printing to dosimetry in radiation oncology. Methods: A thorough search across four databases identified 601 relevant publications. After removing duplicates using Rayyan QCRI and screening for relevance, 52 full-text articles were reviewed and six met the eligibility criteria for evidence synthesis. Results: The review covered six studies, including 76 cancer patients in total, of whom 52 (68.4%) were females. The studies indicated that 3D-printed boluses improved dose accuracy, skin conformity, and toxicity management during postmastectomy chest wall radiation. For scalp malignancies, integrated bolus/headrests minimized air gaps and enhanced treatment reproducibility. Customized boluses for squamous cell carcinomas (SCCs) in the extremities were adapted to anatomical variations, thereby increasing precision. Tongue immobilization devices reduced mucosal exposure in patients with nasopharyngeal cancer, outperforming standard mouthpieces. Patient-specific phantoms refined dose calculations, whereas 3D-printed nose boluses enabled cost-effective, highly controlled nasal cancer treatments with low toxicity. Conclusion: 3D printing is transforming radiation oncology by enhancing precision, personalization, and clinical performance. It addresses key challenges, such as dose conformity, reproducibility, and patient comfort. Despite its limitations, the benefits of 3D printing emphasize its future role as a vital tool in radiation therapy.