Bioactive peptides-based drugs, being a novel therapeutic approach as an alternative to conventional chemotherapy, are the next-generation option. In this milieu, the present study was designed to evaluate the anti-tumoral activities of Water-Soluble Peptides (WSPs) derived from casein, whey, fish bones, and mixed WSPs in 7,12-dimethylbenz (a) anthracene (DMBA)-induced mammary carcinoma. The mammary carcinoma was induced in rats by administering 60mg/kg DMBA by dividing into two doses intra-gastrically through gavage. The rats were divided into 6 groups: G₀ (Negative control), G₁ (Doxorubicin receiving rats), G₂ (Casein WSPs extract), G₃ (Whey WSPs extract), G₄ (Fish bones WSPs extract), and G₅ (Mixed WSPs). Physical parameters and biochemical assays were performed at three intervals (1^st, 6^th, and 12^th week). The WSPs significantly (p<.001) improved the activity of antioxidant enzymes in carcinogenic animals. Furthermore, the fish and mixed WSPs also prevented the increase in the concentration of tumor biomarkers that are carcinoembryonic antigen (CEA), erythrocyte sedimentation rate (ESR), and p53 in experimental rats. Continual increase in liver function enzymes was also observed in G₁ and G₂ as compared to G₄ and G₅. The immunohistochemical analysis was also conducted to assess the expression of proteins related to epigenetic alterations. The results revealed that p53 protein expression decreased in G₁ and G_5, whereas the expression of breast cancer gene-1 (BRCA1) and breast cancer gene-2 (BRCA2) increased in G₁, G_4, and G₅ due to increased immunoreactivity and well-defined nuclear staining. This can be concluded from the findings that G₄ and G₅ exhibited the strong hepatic toxicity mitigation potential as compared to G₁. This study opens the window to consider bioactive peptides for the development of functional foods or new drugs for anticancer therapy.