ABSTRACT Student evaluations of teaching (SETs) are widely used in higher education to assess instructional effectiveness and inform faculty personnel decisions. However, the factors influencing SETs remain a topic of ongoing research. This study investigated the predictive role of students’ motivation-related perceptions, as conceptualised by the MUSIC model (eMpowerment, Usefulness, Success, Interest, and Caring), and course difficulty in explaining variability in course and instructor evaluations. Participants included 2,949 undergraduate students from 30 courses across various disciplines at a large public university in the United States. Hierarchical linear modelling analyses revealed that students’ perceptions of the MUSIC components were significant predictors of both course and instructor evaluations at the student and course levels. Perceived course difficulty was negatively associated with evaluations, but the effect was smaller compared to the motivation-related variables. The final models explained substantial proportions of variance in course (67.6%) and instructor (65.2%) evaluations at the course level. The findings highlight the importance of fostering a motivationally supportive classroom environment to enhance students’ perceptions of empowerment, usefulness, success, interest, and caring, which in turn, can lead to more favourable evaluations of teaching effectiveness. SETs should be used as a tool to inform instructors’ pedagogical decisions rather than for personnel evaluation. Limitations and future research directions are discussed, including examining the influence of student diversity on SETs and referencing more recent literature.