Cancer, a major challenge to global health and healthcare systems, requires the study of alternative and supportive treatments due to the limitations of conventional therapies. This review examines the chemopreventive potential of three natural compounds: rosmarinic acid, apigenin, and thymoquinone. Derived from various plants, these compounds have demonstrated promising chemopreventive properties in in vitro, in vivo, and in silico studies. Specifically, they have been shown to inhibit cancer cell growth, induce apoptosis, and modulate key signaling pathways involved in cancer progression. The aim of this review is to provide a comprehensive overview of the current research on these phytochemicals, elucidating their mechanisms of action, therapeutic efficacy, and potential as adjuncts to traditional cancer therapies. This information serves as a valuable resource for researchers and healthcare providers interested in expanding their knowledge within the field of alternative cancer therapies.