According to recent studies, the Plantaginaceae, which are traditional Chinese herbal remedies, have potential for use in viral infection treatment and cancer therapy. Linalool and p-coumaric acid are two of the biologically active compounds that can be isolated from the Plantaginaceae. This study mainly focused on investigating the bioactivity of linalool as well as the bioactivity of p-coumaric acid in terms of their cytotoxic effects on cancer cells. Whether the mechanisms of such effects are generated through apoptosis and immunoregulatory activity were also investigated. By using WST-1 analysis, it was shown that linalool and p-coumaric acid have good inhibitory effects against breast, colorectal and liver cancer cells. The IC50 values of linalool for those cancer cell types were 224 μM, 222 μM, and 290 μM, respectively, and the IC50 values of p-coumaric acid were 693 μM, 215 μM and 87 μM, respectively. Cell cycle analysis also confirmed that linalool and p-coumaric acid can lead to apoptosis. By using flow cytometry, it was determined that treatment with linalool rather than p-coumaric acid significantly increased the sub-G1 phase and that there were more cells concentrated in the G1 phase. Furthermore, by using cytokine array analysis, we found that linalool can stimulate IFN-γ, IL-13, IL-2, IL-21, IL-21R, IL-4, IL-6sR and TNF-α secretion. This demonstrated that in addition to the bidirectional regulation capabilities found in linalool, it also induces Th1 cellular immune response in T-47D cells. These results showed that linalool holds great potential for use in cancer therapy, and we believe that it could provide an alternative way to take action against tumors.