Currently, nanoscience is a major part of biomedical research, due to material advances that aid the development of new tools and techniques to replace traditional methods. To this end, the potential of porous silicon nanoparticles (pSiNPs) has been examined, especially in areas of cancer treatment and diagnosis. The properties of pSiNPs such as their porous structure, high surface area and porous volume, biocompatibility and biodegradability offer real opportunities for focal therapies that can avoid the side effects caused by conventional methods. This review is focused on pSiNPs and their potential application in targeted anticancer drug delivery, and photodynamic and thermal therapies. In addition, the luminescence properties of pSiNPS are useful in bioimaging and diagnosis. Hence, the theranostic potential of pSiNPs is discussed herein.