Although Sanggenol L (SL), derived from the root bark of Morus alba, has hepatoprotective, neuroprotective, and antitumor effects, the antitumor mechanism of SL remains unclear to date. Thus, in the current work, the apoptotic mechanisms of SL were investigated in HepG2 and Huh hepatocellular carcinoma (HCC) cells in relation to leucine-rich repeat containing G protein-coupled receptor 5 (LGR5)/β-catenin and miR134 signaling axis. Herein, SL significantly incremented cytotoxicity, sub-G1 population, and the number of terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) positive apoptotic bodies and also inhibited proliferation in HCCs. Consistently, SL activated pro-Caspase7 and pro-Caspase3 and induced the cleavage of Poly ADP-ribose polymerase (PARP) in HCCs. Of note, the pivotal role of LGR5/β-catenin signaling was verified in SL-induced apoptosis in LGR5 overexpressed AML-12 cells and LGR5 depleted HepG2 cells. Furthermore, SL upregulated miR134 expression levels in HepG2 cells, while miR134 inhibitors disturbed the capacity of SL to cleave PARP and pro-Caspase3 in HepG2 cells. Taken together, our findings highlight evidence that inhibition of the LGR5/β-catenin axis and upregulation of miR134 play critical roles in SL-induced apoptosis in HCCs.