People with cerebellar degeneration show characteristic ataxic motor impairments. Despite cerebellar dysfunction, they can still improve motor performance through sensorimotor training. Yet, how such training affects functional brain networks affected by cerebellar degeneration is unknown. We here investigated neuroplastic changes in the cortico-cerebellar network after a five-day forearm movement training in 40 patients with mild to severe cerebellar degeneration and 40 age- and sex-matched healthy controls. Human participants (41 female) were assigned to one of four motor training conditions, varying online visual feedback and explicit verbal feedback. Anatomical and resting-state fMRI was collected on the days before and after training. To overcome the limitations of standard brain templates that fail in the presence of severe anatomical abnormalities, we developed a specific template for comparing cerebellar patients with age-matched controls. Our new template reduced the spatial spread of cerebellar anatomical landmarks by 30% relative to existing templates and tripled fMRI noise classification accuracy. Using this pipeline, we found that patients showed impaired connectivity between cerebellar motor regions and neocortical visuomotor and premotor regions at baseline compared to controls, whereas their cortico-cortical connectivity remained intact. Training with vision strengthened connectivity in the cortico-cerebellar visuomotor network contralateral to the trained arm in all participants. Cerebellar patients exhibited additional increased connectivity ipsilateral to the training arm in this network. Further, training with explicit verbal feedback affected connectivity between a cerebellar cognitive region and dorsolateral prefrontal cortex, although post-hoc tests did not show a significant difference. These results document enhanced cortico-cerebellar connectivity as a neurophysiological response to visuomotor training in people with cerebellar degeneration. Significance Statement Despite cerebellar dysfunction, patients with cerebellar degeneration can still improve motor function with training. However, the neuroplastic changes in the brains of cerebellar patients underlying these training effects are largely unknown. Using a specialized brain template and a large patient-control sample, this study demonstrates that sensorimotor training increases connectivity in the cortico-cerebellar network of cerebellar patients, specifically between cortical and cerebellar regions where patients show impairments at baseline. Importantly, these changes were feedback-dependent, with visuomotor training increasing connectivity contralaterally in all participants and ipsilaterally in cerebellar patients. This work provides critical insights into how targeted interventions can engage residual brain function in cerebellar degeneration. Additionally, the novel brain template offers a valuable tool for future neuroimaging studies of cerebellar degeneration.