Background: Cancer incidence and mortality are steadily increasing both globally and in Mongolia. As these rates rise, traditional Mongolian medicine has long utilized herbal formulas for the treatment of gastric and esophageal cancers and precancerous conditions. One such formulation—Hot Natured 3 Herbs (HN3H)—comprises three species from the Ranunculaceae family: Atragene sibirica L., Ranunculus repens L., and Pulsatilla bungeana L.. However, scientific validation of its anti-tumor effects is essential. This study aimed to investigate the effect of HN3H in a tumor-induced animal model. Aim: To identify the biologically active compounds of HN3H and evaluate their effect in an experimentally induced tumor model in animals. Materials and Methods: The three herbs comprising HN3H—Atragene sibirica L., Ranunculus repens L., and Pulsatilla bungeana L.—were collected during their flowering stage (May–June) in Khishig-Undur, Bulgan province, and dried according to official procedures. Extraction was carried out by maceration in 96% ethanol at a 1:10 ratio. The concentrated extract was suspended in water (1:1) and successively fractionated with dichloromethane, ethyl acetate, butanol, chloroform, and n-hexane. The study was approved by the Research Ethics Committee of the Mongolian National University of Medical Sciences (Protocol №2020/03-04). A colorectal cancer model was established by subcutaneous injection of MC-38 cells (Kerafast, USA) into C57BL/6 mice. Immunohistochemistry was performed using CK20, CDX2, Ki67, and p53 antibodies at 1:100 and 1:200 dilutions. Results: The ethanol extract of HN3H contained 2.98±0.04% total phenolics and 2.16±0.05% total flavonoids. Body weight and tumor volume were measured daily with three repetitions. All groups showed a time-dependent increase in body weight. Mice in groups 1A and 1B received ethanol extract at 50 and 100 mg/kg doses; groups 2A and 2B received dichloromethane extract at the same doses. The negative control group was administered 0.5 mg/kg PBS orally, while the positive control group received intraperitoneal injections of 5-fluorouracil (5FU) at 10 mg/kg twice a week. Tumor growth increased in a time-dependent manner across groups. Compared to the negative control, tumor volumes in four treatment groups showed statistically significant reduction (p˂0.05), while no significant difference was observed when compared to the positive control (p=0.08). Histological analysis revealed necrosis in all groups, with variation in extent. Conclusion The ethanol extract of HN3H exhibited moderate levels of phenolic compounds and a high concentration of flavonoids. HN3H extract inhibited tumor progression and activated lymphocyte-predominant inflammation in tumor tissues, indicating potential anti-tumor activity (p˂0.05).