Issue addressed Evidence suggests that physical activity (PA) and sedentary behaviour (SB) participation varies among culturally and linguistically diverse (CALD) adolescents. The present study examined differences in PA and SB among a CALD sample of Chinese Australian, South-east Asian and Anglo-Australian adolescents. Methods Data from 286 adolescents aged 12-16 years involved in the Chinese and Australian Adolescent Health Survey in metropolitan Melbourne, Australia, were analysed. Accelerometry outcomes included median activity counts per minute (counts.min-1) and minutes per day (min.day-1) spent in light-intensity PA (LPA), moderate-to-vigorous-intensity PA (MVPA) and sedentary time (ST). Kruskal-Wallis one-way analysis of variance and sequential multiple hierarchical linear regressions were used to examine CALD differences in PA and ST. Results Multivariate analyses of accelerometry data found Chinese Australian and South-east Asian adolescents engaged in significantly less daily MVPA (5-8min.day-1) and LPA (50-58min.day-1; P<0.05), but greater daily ST (40-41min.day-1), than Anglo-Australian adolescents, after adjusting for age, gender and socioeconomic category. Conclusion The results demonstrate lower engagement in daily MVPA and LPA and greater engagement in ST using accelerometry among Chinese Australian and South-east Asian adolescents compared with Anglo-Australian adolescents. These findings have important public health implications in furthering our understanding of CALD differences in PA and SB. So what? An understanding of the CALD differences in physical activity and sedentary behaviour among Australian adolescents has important implications for intervention planning and delivery as well as the wider health implications of these behaviours. This article furthers the current understanding of CALD adolescents' participation in physical activity and sedentary behaviour, of which limited information is available.