Problem behaviors and the risk of learning disorders in early childhood carry significant implications for children’s future development. Understanding the relationship between parenting stress and these developmental outcomes may inform the design of effective interventions to promote healthy child development. The present longitudinal study investigated the association between parenting stress and preschoolers’ risk of learning disorders, specifically focusing on the mediating role of problem behaviors. Data were collected at two time points, approximately 6 months apart, from 284 preschool-aged children and their parents (mean age of children at Time 1 = 56.64 months; 53.17% of them were girls). Parents completed standardized assessments of parenting stress, children’s problem behaviors, and the risk of learning disorders. An autoregressive cross-lagged panel model within a half-longitudinal framework was employed to test the hypothesized mediation model. Results revealed that parenting stress had a direct effect on both children’s problem behaviors and their risk of learning disorders. Moreover, children’s problem behaviors partially mediated the longitudinal association between parenting stress and learning disorder risk. Specifically, the indirect effect size was statistically significant (β = 0.022, p = 0.025), indicating that increased parenting stress contributed to approximately a 2.2% increase in the risk of learning disorders through elevated problem behaviors. Theoretically, these findings underscore the critical role of child behavioral adjustment as a mechanism through which parenting stress may influence developmental risk. The results highlight the potential benefits of reducing parenting stress and addressing children’s behavioral difficulties to prevent early learning problems. However, the study relied exclusively on parent-reported data, which may introduce shared method variance and reporting bias; future research should incorporate multiple informants and objective behavioral assessments.