Objective: To investigate the cytotoxic activity and molecular mechanism(s) of two Thai noni juice (TNJ) products ethanolic extracts against cholangiocarcinoma (CCA) cell lines and non-cancerous cells, and to explore phenolic acid compositions of TNJ products. Methods: Phenolic acid profiles of TNJ Chiangrai (TNJ-Cr) and TNJ Buasri (TNJ-Bs) ethanolic extracts were determined by HPLC. The cytotoxicity of TNJ ethanolic extracts on cancer and non-cancerous cells was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and trypan blue assays. Mechanism(s) underlying the anti-CCA activity of TNJ ethanolic extracts were determined by cell cycle, apoptosis, and reactive oxygen species (ROS) generation assays. The expression levels of proteins involved in apoptosis and ERK signaling were evaluated by Western blot analysis. Results: Phenolic acid profiles of both TNJ ethanolic extracts showed that the p-hydroxybenzoic, vanillic, and protocatechuic acids were the major phenolic acids in TNJ products. Cytotoxicity assays revealed that the TNJ-Cr and TNJ-Bs ethanolic extracts reduced viability of CCA cell lines through induction of apoptosis by up-regulation of p53 and Bax proapoptotic proteins. Both TNJ ethanolic extracts promoted ROS generation by activating the ERK1/2 signaling in well-differentiated CCA cells KKU-213B. Meanwhile, TNJ ethanolic extracts did not induce ROS production in poorly differentiated CCA cells KKU-100. Both TNJ ethanolic extracts showed no toxicity to human peripheral blood mononuclear cells. Conclusions: TNJ ethanolic extracts could inhibit CCA cell proliferation by inducing ROS generation and apoptosis and may be applicable for combination therapies in CCA treatment.