Research has revealed a negative association between appearance-related social media consciousness (ASMC) and mental health, but the impact of this association in the Chinese population remains understudied. This study examined the psychometric properties of the ASMC scale among Chinese adolescents and young adults and to further investigate the scale’s measurement invariance and differences in ASMC across gender and age groups. Exploratory and confirmatory factor analyses were conducted to examine the ASMC scale’s factorial structure among Chinese adolescents and young adults, including 1109 adolescents (50.0% boys) aged 12–18 (mean, 14.89) years and 457 young adults (42.5% men) aged 18–25 (mean, 20.75) years. The measurement invariance across gender and age groups, internal consistency and convergent validity were examined. ASMC scale was found to have a unidimensional structure and to be invariant across gender and age groups. It exhibited excellent internal consistency and strong construct validity. Moderate gender differences and pronounced age differences in ASMC scale scores were observed. Our findings support the validity of the ASMC scale as an effective instrument for the measurement of appearance-related social media consciousness experience among Chinese young adults and adolescents. Further study is required to evaluate the status of ASMC as a risk factor for disordered eating and target for preventive interventions within Chinese samples.