Objectives <p>Equanimity, a contemplative outcome of mindfulness-based interventions, is crucial for the mental health and well-being of adolescents. However, there is a lack of direct measurement tools for assessing equanimity levels among Chinese adolescents. The Equanimity Scale-16 (ES-16), which includes Experiential Acceptance and Non-reactivity as two sub-scales, has shown good psychometric properties in previous studies. This paper aimed to adapt and validate a Chinese version of the ES-16 for adolescents.</p> Method <p>A total of 4206 (2823 valid) Chinese adolescents were recruited online. After forward and backward translations, the Chinese version of the ES-16 was then tested for internal consistency, factor structure, criterion-related validity, and test–retest reliability.</p> Results <p>Analyses of reliability, exploratory factor analysis and confirmatory factor analysis indicated that removing 2 items (NR1 and NR2) from the original Non-reactivity sub-scale would enhance the psychometric integrity. After removal, the modified scale, namely the ES-14(C), exhibited good internal consistency, reliability, and validity among Chinese adolescents (CFI = 0.986, TLI = 0.983, RMSEA = 0.044 [90% CI: 0.040, 0.049]).</p> Conclusions <p>After adaptation, the Chinese 14-item Equanimity Scale (ES-14(C)) for adolescents was obtained. The ES-14(C) is a psychometrically sound instrument for assessing equanimity in Chinese adolescents, showing promise for use in clinical research and psychotherapy.</p> Preregistration <p>This study is not preregistered.</p>