Burnout impairs English as a foreign language (EFL) learning, while engagement enhances it. However, most relevant studies have focused on college students, neglecting senior high school students. To address this gap, this mixed-methods study used two scales to assess the levels of burnout and engagement among 1234 Chinese senior high school EFL students. We also applied a person-centered approach with a statistical software (Mplus 8.7) to identify their latent profiles. Then, we conducted semi-structured interviews with 30 students and analyzed the data using thematic analysis with a qualitative software (MAXQDA 2022) to investigate the antecedents of their burnout and engagement. The statistical analysis revealed three profiles: high burnout-low engagement (16.0 %), moderate burnout-moderate engagement (61.8 %), and low burnout-high engagement (22.2 %). The profiles were associated with demographic characteristics such as gender, age, and grade. The thematic analysis identified four major antecedents: high academic stress and low academic support for burnout, and high external support and high internal support for engagement. Each major antecedent consisted of several categories and subcategories. This study could inform the design of effective interventions to reduce Chinese EFL students' burnout and increase their engagement.