<p>While previous research suggests a potential interplay between motivation, depression, and anxiety, little research has comprehensively examined these relationships among young adult offenders. This study employed the Random Intercept Cross-Lagged Panel Model to investigate the bidirectional causal relationships between motivation to succeed, depression, and anxiety, exploring both between-person and within-person levels. Utilizing a nationally representative longitudinal dataset of young adult offenders (<i>n</i> = 1,249; 85.62% male), data were collected at four timepoints covering developmental stages from adolescence to adulthood. Our findings indicate that higher levels of depression and anxiety predict decreased motivation to succeed, while motivation is associated with lower levels of subsequent depression and anxiety, though individual variations exist. Bidirectional relationships between anxiety and depression were also observed, reinforcing the need for integrated interventions. These findings provide important implications for tailored rehabilitation strategies aimed at improving mental health and motivation among young adult offenders, contributing to more effective support and reduced recidivism.</p>