IntroductionBased on the Combined Cognitive Biases Hypothesis, the current study via two parallel studies aims to explore the potential mediating role of attention biases and attention control regarding the link between trait mindfulness and psychological stress in adolescents.MethodsFor Study 1, we collected self‐reported data from 2123 Chinese adolescents (mean age = 15.6 years, SD = 2.37; 52.8% female) in four schools. The participants completed measures of trait mindfulness, perceived stress, and attention bias. Mediation analysis was employed to investigate the potential mediating effect of attention bias. In Study 2, 123 participants (mean age = 17.7 years, SD = 2.68; 41.46% female) completed the attention network task after inducing attention bias. Then, trait mindfulness and perceived stress were measured. Mediation analysis was employed to investigate the potential mediating effect of attention control (alerting, orienting, and conflict monitoring) under attention bias.ResultsStudy 1 demonstrated a significant mediating effect of negative attention bias ([−0.13, −0.07], p < .05) but not positive attention bias in the relationship between trait mindfulness and psychological stress. Study 2 revealed that conflict monitoring in negative attention bias ([−0.41, −0.16], p < .05), rather than alerting and orienting in negative attention bias, showed a significant mediating effect on the association between trait mindfulness and psychological stress.ConclusionsFindings from the two studies suggest that conflict monitoring during negative attention bias may be the underlying mechanism through which trait mindfulness helps mitigate psychological stress in adolescents.