The GPi-LHb pathway is the main output of the basal ganglia suggested to shape motivated behaviors. We here show that somatostatin-expressing (Sst+) GPi-LHb neurons project to key nodes in the basal ganglia: the GPe, the striatal striosomes, and dopamine neurons in the SNc. Calcium imaging coupled with unsupervised behavioral segmentation revealed that activity of Sst+ GPi-LHb neurons is strongly linked with motor actions during exploration in an open field arena. On the other hand, in a maze-based choice task, the activity of Sst+ GPi-LHb neurons showed a gradual suppression over days as mice increased their accuracy. Interestingly, the calcium transients recorded before the choice increased in amplitude after reversal, despite the animal executing the same movements. Chronic silencing of the Sst+ GPi-LHb induced an increase in the number of errors and a consequent decrease in the accuracy after reward reversal. All together, our data suggest a role of Sst+ GPi-LHb pathway during motor actions but also in adapting choice-behavior and seeking alternative reward locations.