Exposure-based CBT is effective in treating anxiety disorders, but individual responses vary substantially, underlining the need to identify and boost mechanisms underlying exposure. In this study, the role of positive emotions occurring after exposure was examined. In an analysis of 8416 exposure records of 648 anxiety patients undergoing exposure therapy, the degree of positive emotions hope and joy occurring after exposure exercises, their predictors, and their role regarding treatment success were investigated. Positive emotions after exposure were medium to high and increased slightly across repeated exposure exercises. They were associated with exposure-related learning indicators (i.e., expectancy violation and change as well as the prediction-error learning rate) and were mainly predicted by adjusted threat expectancy assessed after completing exposure, controlling for baseline depressive symptoms and affect. Higher positive emotions independently predicted better treatment outcome beyond learning indicators, and partially mediated the association between learning indicators and treatment outcome. These findings indicate that positive emotions are partly associated with successful learning during exposure but seem to have a unique contribution to overall treatment success, underlining the need to strengthen positive emotions via different possible means.