Autonomy supportive teaching practices are associated with a variety of positive student outcomes. Past research has identified various intrapersonal, interpersonal, and environmental factors that contribute to instructors’ use of autonomy support. However, the extent to which instructor affect predicts changes in their use of autonomy support, as well as the reverse, has yet to be examined. In the current study, we surveyed 405 college instructors across two timepoints during the Spring 2022 semester to examine the reciprocal relationships between instructors’ positive and negative affect during class and their use of autonomy support. Cross-lagged panel models suggested that instructors’ use of autonomy support predicted an increase in overall positive affect during class over time, while instructors’ overall positive affect in class did not predict an increase in autonomy support in class over time. Reciprocal relationships emerged for the specific affective states of feeling content and determined in class. No relationships between instructor negative affect and their use of autonomy support emerged in either direction. Results highlight the importance of examining the ways in which instructors’ positive affect shape instructional behaviors and the benefits that instructors may experience when implementing autonomy support in the classroom.