Huntington's disease (HD), a neurodegenerative disorder caused by an expanded CAG repeat in the huntingtin gene, impairs information processing in the striatum, which, as part of the basal ganglia, modulates motor output. Growing evidence suggests that huntingtin interacting protein 14 (HIP14) contributes to HD neuropathology. Here, we recorded local field potentials (LFPs) in the striatum as HIP14 knockout mice and wild-type controls freely navigated a plus-shaped maze. Upon entering the choice point of the maze, HIP14 knockouts tend to continue in a straight line, turning left or right significantly less often than wild-types, a sign of motor inflexibility that also occurs in HD mice. Striatal LFP activity anticipates this difference. In wild-types, the power spectral density pattern associated with entry into the choice point differs significantly from the pattern immediately before entry, especially at low frequencies (≤13 Hz), whereas HIP14 knockouts show no change in LFP activity as they enter the choice point. The lack of change in striatal activity may explain the turning deficit in the plus maze. Our results suggest that HIP14 plays a critical role in the aberrant behavioral modulation of striatal neuronal activity underlying motor inflexibility, including the motor signs of HD.