Background: Although chemotherapy and targeted therapies have improved survival outcomes, there is growing interest in incorporating herbal medicines, such as Artemisia annua, into cancer treatment. Objectives: This study aims to investigate the mechanisms underlying the effects of A. annua methanolic extract on HT-29 colorectal cancer cells, particularly focusing on cell viability and the modulation of p53 and BAX/Bcl2 ratio expression. Methods: The half-maximal inhibitory concentration (IC50) of A. annua methanolic extract in HT-29 cells was determined via the MTT viability assay, while apoptosis was assessed using the propidium iodide (PI) staining method. Reverse transcription (RT)-PCR was performed to evaluate gene expression in the HT-29 cell line. Values are presented as the average of three separate determinations and expressed as mean ± SD. Results: The results showed that the viability of HT-29 cells significantly decreased in a dose- and time-dependent manner (IC50 for 48 h: 1358.1 μg.mL-1). Propidium iodide staining results confirmed the findings of the MTT assay. Gene expression analysis revealed a decrease in p53 expression and a two-fold increase in the BAX/Bcl2 ratio following exposure to 1000 μg.mL-1 of A. annua extract. Conclusions: The findings from the MTT and PI assays confirm the cytotoxic effects of A. annua extract on HT-29 cells. However, the gene expression analysis of BAX, Bcl2, and p53 suggests that the observed cell death is not primarily due to apoptosis.