The H3K27 lysine-specific demethylase UTX is targeted by loss-of-function mutations in multiple cancers. Here, we demonstrate that UTX suppresses myeloid leukemogenesis through non-catalytic functions, a property shared with its catalytically inactive Y-chromosome paralogue, UTY. In keeping with this, we demonstrate concomitant loss/mutation of UTX and UTY in multiple human cancers. Mechanistically, global genomic profiling revealed only minor changes in H3K27Me3, but significant and bidirectional alterations of H3K27Ac and chromatin accessibility, a predominant loss of H3K4Me1 modifications, alterations in ETS and GATA factor binding and altered gene expression upon Utx loss. By integrating proteomic and genomic analyses, we link these changes to UTX regulation of ATP-dependent chromatin remodeling, coordination of the COMPASS complex and enhanced pioneering activity of ETS factors during evolution to AML. Collectively, our findings reveal a dual role for UTX in suppressing acute myeloid leukaemia via repression of oncogenic ETS and upregulation of tumor-suppressive GATA programs