Biomarker-driven molecular imaging probes play a crucial role in precision radiotherapy by enabling the non-invasive monitoring of tumor biomarkers and their responses to radiation. This review summarizes the current state of research on imaging biomarkers and molecular imaging probes in radiotherapy, highlighting their potential for improving treatment outcomes and reducing adverse effects. The review discusses various imaging biomarkers, including those related to hypoxia, metabolic responses, tumor-associated surface receptors, radioresistant cell types, and radiosensitive factors. These biomarkers are essential for radiotherapy planning, patient stratification, response assessment, and toxicity prediction. The review also explores the development of molecular imaging probes, such as nanoprobes, which can be activated by specific biomarkers to provide dynamic and spatiotemporal information for personalized therapy. The review emphasizes the importance of validating imaging biomarkers and developing rational probe designs to enhance the accuracy and effectiveness of radiotherapy. The integration of advanced imaging techniques, such as PET, MRI, and photoacoustic imaging, with biomarker-driven approaches is crucial for improving the precision and outcomes of radiotherapy. The review concludes that further research is needed to establish the correlation between imaging biomarkers and radiotherapy outcomes, as well as to develop robust and extensive investigations to validate these biomarkers and their associated probes.Biomarker-driven molecular imaging probes play a crucial role in precision radiotherapy by enabling the non-invasive monitoring of tumor biomarkers and their responses to radiation. This review summarizes the current state of research on imaging biomarkers and molecular imaging probes in radiotherapy, highlighting their potential for improving treatment outcomes and reducing adverse effects. The review discusses various imaging biomarkers, including those related to hypoxia, metabolic responses, tumor-associated surface receptors, radioresistant cell types, and radiosensitive factors. These biomarkers are essential for radiotherapy planning, patient stratification, response assessment, and toxicity prediction. The review also explores the development of molecular imaging probes, such as nanoprobes, which can be activated by specific biomarkers to provide dynamic and spatiotemporal information for personalized therapy. The review emphasizes the importance of validating imaging biomarkers and developing rational probe designs to enhance the accuracy and effectiveness of radiotherapy. The integration of advanced imaging techniques, such as PET, MRI, and photoacoustic imaging, with biomarker-driven approaches is crucial for improving the precision and outcomes of radiotherapy. The review concludes that further research is needed to establish the correlation between imaging biomarkers and radiotherapy outcomes, as well as to develop robust and extensive investigations to validate these biomarkers and their associated probes.