Background Painful temporomandibular disorder is common, but cerebellar responses to different mandibular states remain insufficiently described. This case is reported because it shows a novel within-subject pattern of state-dependent cerebellar blood oxygen level-dependent signal redistribution.Case presentation: A 27-year-old woman presented with persistent jaw tension, bruxism, and subjective chronic tinnitus of approximately 2 years duration. Brain magnetic resonance imaging with task-based functional imaging was performed using a block-design rest-task paradigm. During imaging, the patient performed jaw-closing tasks under three experimentally defined mandibular conditions: centric occlusion, a splint condition, and centric relation. Functional data were preprocessed in standard space and analyzed using voxelwise and region-of-interest-based cerebellar assessment with the SUIT Nettekoven Asym32 atlas. The splint condition showed the largest number of cerebellar clusters and the broadest topographic distribution, but these activations were mainly small and spatially fragmented. Centric relation showed the largest total activated volume and the highest peak signal, consistent with more consolidated activation fields. Centric occlusion showed fewer clusters overall but the highest mean signal intensity. Model-based analysis did not identify a robust global main effect of mandibular condition; however, region-specific effects and an interaction between cerebellar region and centric relation suggested condition-dependent redistribution of cerebellar activity.Conclusions This case demonstrates that cerebellar blood oxygen level-dependent responses in painful temporomandibular disorder may vary according to mandibular state in a region-specific manner. The findings provide pathophysiological insight into cerebellar involvement in temporomandibular disorder and suggest potential value for individualized functional assessment in complex cases.