Targeting the MYST acetyltransferases are an exciting therapeutic opportunity in acute myeloid leukaemia (AML). Here we define the individual and combined contribution of KAT6A, KAT6B and KAT7, in a range of AML models showing that while KAT6A/B inhibition is efficacious in some pre-clinical models, simultaneous targeting of KAT7, with the novel inhibitor PF-9363, markedly increases efficacy. KAT7 interacts with Menin and the MLL complex and is co-localised at chromatin to co-regulate oncogenic transcriptional programs. Focusing on MLL fusion oncoprotein (MLL-FP) AML, we show that inhibition of KAT6/KAT7 provides an orthogonal route to targeting Menin to disable the transcriptional activity of the MLL-FP. Combined inhibition rapidly evicts the MLL-FP from chromatin, potently represses oncogenic transcription and overcomes primary resistance to Menin inhibitors. Notably, KAT7 remains an important targetable dependency in acquired genetic/non-genetic resistance to Menin inhibition providing the molecular rationale for rapid clinical translation of combination therapy, particularly in MLL-FP AML.