In addition to its metabolic functions, recent research highlights vitamin D’s wide range of effects, including its anticancer properties. Calcitriol, the active form of vitamin D3, affects gene expression by interacting with VDRs, leading to cellular differentiation, apoptosis, and inhibition of tumor-related processes like inflammation, angiogenesis, and metastasis. Vitamin D’s impact on specific cancers, such as colorectal, breast, and prostate cancer, involves the regulation of molecular pathways that control cell proliferation and hormone sensitivity. In colorectal cancer, calcitriol inhibits the WNT-beta catenin signaling pathway, while in breast cancer, it downregulates aromatase expression. Studies in animal models have shown that vitamin D deficiency may promote tumor growth, and supplementation could hinder cancer progression. However, human-level population studies have been inconclusive. Further research is required to identify the at-risk population that would most benefit from vitamin D.