Colon cancer remains a significant global health challenge; however, the treatment outcome for colon patients can be improved through early detection and effective treatment. Nano-radiopharmaceuticals, combining nanotechnology with radiopharmaceuticals, are emerging as a revolutionary approach in both colon cancer diagnostic imaging and therapy, playing a significant role in the management of colon cancer patients. This review examines the use of nano-radiopharmaceuticals in the diagnosis and treatment of colon cancer, highlighting current applications, challenges, and future directions. Nanocarriers of radionuclides have shown potential in improving cancer treatment, including liposomes, microparticles, nanoparticles, micelles, dendrimers, and hydrogels, which are approved by the FDA. These nanocarriers can deliver targeted drugs into malignant cells without affecting normal cells, reducing side effects. Antibody-guided systemic radionuclide-targeted therapy has shown potential for treating cancer. Novel cancer nanomedicines, like Hensify and 32P BioSilicon, are under clinical development for targeted radiation delivery in percutaneous intratumoral injections. Although using nano-radiopharmaceuticals is a superior technique for diagnosing and treating colon cancer, there are limitations and challenges, such as the unintentional accumulation of nanoparticles in healthy tissues, which leads to toxicity due to biodistribution issues, as well as high manufacturing costs that limit their availability for patients. However, the future direction is moving toward providing more precise radiopharmaceuticals, which is crucial for enhancing the diagnosis and treatment of colon cancer and reducing production costs.