Treatments for major depressive disorder (MDD) target communication between large-scale cortical networks and the cerebellum to improve cognitive control . Here, we examined how repeated-ketamine perturbs cerebro-cerebellar circuitry during response-inhibition using a NoGo/Go task (43 MDD-patients receiving ketamine, 31 controls). We implemented a psychophysiological-interaction analysis to investigate ketamine-related changes in connectivity between cerebellum-regions and cortical-networks and respective nodes. Results showed significant decreases in connectivity between a cerebellum-dorsal-attention region and the default-network. A time-by-response interaction for the somatomotor-network was observed in treatment-responders only. Results support ketamine modulates cerebello-cerebro circuitry, which may be of impact for identifying new biomarkers of MDD response.