K–12 schools implement emergency remote teaching (ERT) amid disruptions to in-person learning, yet there remains little evidence of ERT approaches associated with K-12 students’ more favorable academic and emotional outcomes post-transition. This study identifies ERT strategies supportive of adolescents’ engagement in learning and emotional wellbeing after abruptly shifting to remote learning at the onset of the COVID-19 pandemic. Participants were 206 U.S. high school students (Grades 9–12; 59% female, 91% White, Mgrade = 10.4) who were surveyed two months post-transition. Students self-reported their engagement and positive affect relative to before and after the transition, as well their remote learning participation and opportunities, home support and resources, daily routines, technological access, confidence, and attitudes. Principal Components Analysis (PCA) was utilized to identify five distinct patterns among students’ ERT experiences immediately post-transition: Teacher transitional support, Zoom-heavy, Heavy workload, Chaotic, and Heavy social load. Subsequent regression analyses revealed Teacher transitional support was the only ERT approach significantly associated with high schoolers’ greater engagement and positive affect post-transition. Heavy workload and Heavy social load ERT predicted students’ higher engagement, but not positive affect, post-transition. Neither Zoom-heavy or Chaotic ERT exhibited significant associations with either post-transition outcome. Hierarchical regression models further revealed differences in students’ ERT experiences at the onset of the pandemic explained as much variance in students’ post-transition engagement as home environmental factors, yet failed to explain significant variance in students’ post-transition positive affect. These findings underscore the role of well-structured, emotionally supportive ERT for supporting adolescents’ academic engagement during emergency shifts to remote learning, as well as clarifies the relative contributions of ERT, home, and individual-level factors to adolescents’ academic and emotional adjustment at the start of the COVID-19 pandemic.