Introduction/Objective: Plants and their bioactive compounds play a crucial role in the pharmaceutical industry for treating cancer. To date, the cytotoxic and antiproliferative effects of Hypericum perforatum methanol extract on human thyroid cancer cell lines have not been thoroughly explored. The present study aimed to assess the potential anti-cancer effects of HPME on human thyroid cancer and investigate its potential therapeutic benefits. Methods: HPME was prepared using the maceration method, and its antioxidant activity was examined. Cytotoxicity studies were then carried out, followed by an investigation of the possible effects of HPME on metastasis and colony-forming capacities of human thyroid cancer cells. Afterward, qRT-PCR, western blotting, and apoptosis assays were performed. Results: Cytotoxicity studies revealed notable cytotoxicity of HPME against the TT cell line. Moreover, HPME significantly curtailed metastasis and invasion of TT cells in an in vitro wound healing assay. Analyses of gene expressions demonstrated an elevation in caspase-12, caspase-3, and Bax, coupled with a reduction in BcL-2, APOE, and CLU expression. Following HPME treatment, there was an increase in the protein expression levels of Bax and Caspase-12, while a decrease in the BcL-2, APOE, and CLU protein expression. Furthermore, apoptotic studies indicated an increase in early apoptosis. Conclusion: Overall results revealed that HPME demonstrates a notable antioxidant capacity in human thyroid cancer. It exerts an influence on crucial biological processes associated with cancer, indicating its potential to hinder the proliferation of human thyroid cancer cells by enhancing apoptosis through the upregulation of gene and protein expression, particularly involving caspases.