Autophagy, a self-degradative physiological process, is critical for homeostasis maintenance and energy source balancing in response to various stresses, including nutrient deprivation. It is a highly conserved catabolic process in eukaryotes and is indispensable for cell survival as it involves degradation of unessential or excessive components and their subsequent recycling as building blocks for the synthesis of necessary molecules. Although the dysregulation of autophagy has been reported to broadly contribute to various diseases, including cancers and neurodegenerative diseases, the molecular mechanisms underlying the epigenetic regulation of autophagy are poorly elucidated. Here, we report that the level of lysine demethylase 3B (KDM3B) increases in nutrient-deprived HCT116 cells, a colorectal carcinoma cell line, resulting in transcriptional activation of the autophagy-inducing genes. KDM3B was found to enhance the transcription by demethylating H3K9me2 on the promoter of these genes. Furthermore, we observed that the depletion of KDM3B inhibited the autophagic flux in HCT116 cells. Collectively, these data suggested the critical role of KDM3B in the regulation of autophagy-related genes via H3K9me2 demethylation and induction of autophagy in nutrient-starved HCT116 cells.