Worldwide, colorectal cancer is the third most common cancer in men and the second most common in women. As conventional colorectal cancer therapies result in various side effects, there is a need for adjuvant therapy that can enhance the conventional therapies without complications. In this study, we investigated the anticancer effects of combined mixture of the several medicinal mushrooms and Panax ginseng root extracts (also called Amex7) as an adjuvant compound in the treatment of human colorectal cancer. We observed the in vivo inhibitory effect of Amex7 (1.25, 6.25, and 12.5 ml/kg, oral administration, twice daily) on tumor growth in a mouse model xenografted with HT-29 human colorectal cancer cells. In vitro, at 6, 12, and 24 h after 4% Amex7 treatment, we analyzed cell cycle by flow cytometry and the expression levels of cell cycle progression, apoptosis, and DNA damage repair-related proteins using immunoblotting and immunofluorescence staining in HT-29 cell line. As a result, Amex7 significantly suppressed tumor growth in HT-29 human colorectal cancer cells and xenografts. In vitro, Amex7 induced G2/M arrest through the regulation of cell cycle proteins and cell death by apoptosis and autophagy. Additionally, Amex7 consistently induced DNA damage and delayed the repair of Amex7-induced DNA damage by reducing the level of HR repair proteins. In conclusion, Amex7 enhanced anticancer effects through the induction of G2/M arrest and cell death, including apoptosis and autophagy. Furthermore, Amex7 impaired DNA damage repair. The present study provides a scientific rationale for the clinical use of a combined mixture of medicinal mushrooms and P. ginseng root extracts as an adjuvant treatment in human colorectal cancer.