Despite the growth of blended teaching (BT), little is known about its influences on learning engagement in pre-service teacher education. This study examined changes in the learning engagement of 1285 pre-service teachers (PSTs) at the beginning, middle, and completion of a semester of multiple teaching format transitions amidst COVID-19, and the predictability of individual characteristics and environmental variables, including PSTs’ adaptability, and teacher educators’ self-efficacy and blended teaching behaviors. The data were analyzed using the latent growth model. Results show that levels of vigor and absorption increased significantly over the semester. Individualized teaching behaviors, self-efficacy for instruction, and behavior-cognitive adaptability significantly predicted learning engagement of PSTs. Theoretical and practical implications are discussed.