Abstract: The gastrin-releasing peptide receptor (GRPR) is highly expressed in various malignant tumors (e.g., glioblastoma, prostate cancer, and breast cancer) and has emerged as an important molecular target for precision cancer diagnosis and therapy. In recent years, the combined application of radionuclide-labeled GRPR ligands with positron emission tomography/computed tomography (PET/CT) has achieved groundbreaking progress in noninvasive diagnosis, accurate staging, and therapeutic monitoring of GRPR-positive tumors. Meanwhile, GRPR-targeted radionuclide therapeutics have demonstrated significant therapeutic potential and promising clinical applications in trials. This GRPR-based theranostic strategy pioneers a novel approach for precision medicine in GRPR-overexpressing tumors.