Cerebellar climbing fibers are thought to signal reward prediction errors in non-motor functions. By imaging postsynaptic responses of climbing fibers onto mouse Purkinje cell dendrites during auditory discrimination, we found that climbing fibers in crus I can encode cue identities or perceptual choices. These responses were reshaped by reversal learning. Optogenetic perturbation of climbing fiber activity impaired discrimination. These results suggest a feedforward role of climbing fibers in perceptual decision-making.