Aberrant epigenetic reprogramming occurs frequently in the development of tumors. Histone H3 lysine 27 trimethylation (H3K27me3) exerts a repressive epigenetic mark on a large number of genes. UTX and JMJD3 are the only two histone demethylases which activate gene expression via demethylating H3K27me3 to H3K27me2 or H3K27me1. Current studies show that dysregulation of these two proteins are heavily linked to oncogenesis in various tissue types. Accumulating evidence suggested that there is remarkable therapeutic potential of targeting JMJD3 or UTX in different types of cancer. Herein, we shall give a brief review on the functional roles of JMJD3 and UTX in cancers and evaluate the available compounds and agents targeting UTX and JMJD3. Finally, we also discuss the several modalities that target UTX and JMJD3 for cancer therapy. This review will help to develop novel strategies to abolish or restore effects of UTX and JMJD3 in the pathogenesis of cancer.