Bioactive molecules in foods, nutraceuticals, and pharmaceuticals are gaining importance in recent times owing to the increasing awareness among humans to maintain an immune and a healthy lifestyle. Phytochemicals, also known as phytonutrients, are naturally occurring bioactive substances abundant in various foods, including fruits, vegetables, whole grains, and legumes. These bioactive substances are categorized based on their chemical structures and functions. Some of the most prevalent phytochemicals found in foods are flavonoids, iso-flavonoids, polyphenols, carotenoids, terpenoids, and phytosterols, which are thoroughly studied to assess their impact on human health. They possess antioxidant properties along with anti-inflammatory, antibacterial, and in some cases, anticarcinogenic properties as well. These bioactive ingredients are nutritional components present in food that provide positive health benefits in addition to their fundamental nutritional value. However, only a fraction of numerous thousands of phytochemicals present in plants have been extracted, identified, and studied. Chemoprevention is the application of bioactive molecules to stop, hinder, postpone, reverse, or slow down the development of tumors or cancer-causing agents. Various phytochemicals obtained from edible and medicinal plants have been reported to hinder a certain stage of carcinogenic propagation in human health. Moreover, studying these bioactive compounds for their pharmacological effect, especially their chemopreventive property is of great significance in improving conventional cancer treatment. This study focuses on various bioactive compounds concerning their phytochemical profile and chemopreventive properties for improving human health implications associated with diseases.