Mushrooms are an integral part of Traditional Chinese Medicine (TCM), and have been used for millennia to prevent or treat a variety of diseases. Currently mushrooms or their extracts are used globally in the form of dietary supplements. In the present study we have evaluated the anticancer effects of the dietary supplement, MycoPhyto® Complex (MC), a novel medicinal mushroom blend which consists of a blend of mushroom mycelia from the species Agaricus blazei, Cordyceps sinensis, Coriolus versicolor, Ganoderma lucidum, Grifola frondosa and Polyporus umbellatus, and β-1,3-glucan isolated from the yeast, Saccharomyces cerevisiae. Here, we show that MC demonstrates cytostatic effects through the inhibition of cell proliferation and cell cycle arrest at the G2/M phase of highly invasive human breast cancer cells MDA-MB-231. DNA-microarray analysis revealed that MC inhibits expression of cell cycle regulatory genes (ANAPC2, ANAPC2, BIRC5, Cyclin B1, Cyclin H, CDC20, CDK2, CKS1B, Cullin 1, E2F1, KPNA2, PKMYT1 and TFDP1). Moreover, MC also suppresses the metastatic behavior of MDA-MB-231 by the inhibition of cell adhesion, cell migration and cell invasion. The potency of MC to inhibit invasiveness of breast cancer cells is linked to the suppression of secretion of the urokinase plasminogen activator (uPA) from MDA-MB-231 cells. In conclusion, the MC dietary supplement could have potential therapeutic value in the treatment of invasive human breast cancer.