<p>Fluorodeoxyglucose positron emission tomography (FDG-PET), as a representative biological imaging modality, has demonstrated unique clinical value in the comprehensive management of rectal cancer. This review summarizes the advances in the application of FDG-PET across multiple stages of rectal cancer care, with a focus on its role in assessing stages, guiding radiotherapy plans and predicting prognosis. Although challenges such as coarse granularity of parameters and false positives due to inflammation remain, emerging strategies including dual-time point imaging, multi-modality fusion evaluation, integration with molecular biomarkers, texture analysis, voxel-based modeling, and artificial intelligence have shown promise in overcoming these limitations, and are expected to drive FDG-PET from an auxiliary evaluation tool to a core platform for precision treatment of rectal cancer.</p>