Cancer is one of the leading groups of diseases which occur due to uncontrolled cell proliferation, differentiation, metastasis, apoptosis resistance, angiogenesis, mutations, dysfunction in immunity, therefore resulting in a tumor. Conventional chemotherapy is commonly used as the first line of treatment for cancer patients with some chemotherapeutic drugs, but it shows adverse side effects, such as chemoresistance, radioresistance, stem cell property when healthy cells are exposed to these drugs. With a motive to reduce such side effects ‘adjuvants’ are used in combination with these chemotherapeutic drugs. ‘Phytochemicals’ are plant-derived compounds that are beneficial in adjuvant therapy as they show numerous properties that can control cancer expansion. They act as an epigenetic modulator; they can inhibit those enzymes which regulate cell cycle progression. Furthermore, they induce apoptosis and promote cell cycle arrest in cancerous cells. Curcumin, Emodin, Resveratrol, Nimbolide, Gingerol, EGCG, and a few other Flavonoids, Alkaloids, and Phenols are some plant-derived phytochemicals with the greater potentiality to be used in adjuvant therapy. Through studies and Research, it is visualized that these phytochemicals show chemo-preventive, anti-inflammatory, antioxidant, and anti-cancerous properties by regulating EMT and aggressiveness of cancer cells.