<p>Adolescent mental well-being positively influences physical and psychological development, making it essential to identify its core components for advancing theoretical understanding and designing effective mental well-being improving practices. This study employed cross-lagged panel network (CLPN) analysis to explore the core components within adolescent mental well-being and their gender differences in Chinese context. Using a two-wave longitudinal design with a six-month interval, a total of 2578 adolescents participated in two waves (1422 girls, 1156 boys; T1, <i>M</i>_<i>age</i> = 10.790, <i>SD</i> = 1.266; T2, <i>M</i>_<i>age</i> = 11.229, <i>SD</i> = 1.274) from Sichuan, China. The results revealed that, firstly, <i>feeling cheerful</i> had the highest out Expected Influence (outEI), showing that it was the most influential component in the CLPN. Secondly, <i>feeling relaxed</i> had the highest in Expected Influence (inEI), indicating that it was the component most influenced by other components. Additionally, network comparisons found no significant differences in edge weights between girls and boys, but significant differences were found in the centrality index inEI. Specifically, in girls’ mental well-being CLPN, <i>energy to spare</i> had the highest inEI value, whereas in boys’ mental well-being CLPN, <i>feeling loved</i> had the highest inEI value. These findings offer theoretical implications into adolescent mental well-being, providing practical insights for promoting and improving adolescent mental well-being. Specifically, <i>feeling cheerful</i> could serve as a primary target for enhancing adolescent mental well-being, whereas <i>feeling relaxed</i>, as an easily influenced node, could be used to evaluate practical effectiveness, and considering gender differences can further increase the specificity and precision of related practices.</p>