<p>Porous silicon nanoparticles (pSiNPs) have attracted significant attention as versatile nanocarriers for cancer bioimaging and therapy due to their controllable porosity, high surface area, and unique biodegradability. Based on these properties, pSiNPs enable the efficient loading of various therapeutics and bioimaging probes, including drugs, peptides, nucleic acids, and imaging probes. Furthermore, the easy surface modification of pSiNPs can enhance tumor targeting specificity and enable controlled drug release. Unlike other inorganic nanomaterials that can accumulate in tissues, pSiNPs degrade into biocompatible orthosilicic acid, ensuring excellent in vivo safety. In addition to these properties, the inherent optical properties of pSiNPs allow their use as both drug tracers and optical imaging enhancers. These multifunctional properties have led to rapid advancements in cancer nanomedicine, particularly in the fields of fluorescence, magnetic resonance, and photoacoustic imaging, and have also led to significant advancements in therapeutic modalities such as chemotherapy, immunotherapy, and photo-induced therapy. This review summarizes recent advances in pSiNPs-based cancer bioimaging and therapy, highlighting the structural advantages, imaging capabilities, and therapeutic efficacy of pSiNPs. Furthermore, we examine key challenges and future prospects for clinical application, highlighting the potential of pSiNPs as a next-generation platform for precision oncology.</p>