The prevalence and death due to cancer have been rising over the past few decades, and eliminating tumour cells without sacrificing healthy cells remains a difficult task. Due to the low specificity and solubility of drug molecules, patients often require high dosages to achieve the desired therapeutic effects. Silica nanoparticles (SiNPs) can effectively deliver therapeutic agents to targeted sites in the body, addressing these challenges. Using SiNPs as vehicles for anti-cancer drug delivery has emerged as a promising strategy due to their unique structural properties, biocompatibility, and versatility. This review explores the various aspects of SiNPs in cancer therapy, highlighting their synthesis, functionalization, and application in delivering chemotherapeutic agents, photosensitizers, and nucleic acids. SiNPs offer advantages such as high drug loading capacity, controlled release, and targeted delivery, enhancing therapeutic efficacy and reducing systemic toxicity. Moreover, this review aims to provide an in-depth understanding of the current state and prospects of SiNPs in revolutionizing cancer treatment and improving patient outcomes.