This longitudinal study examined mental health trajectories in a Chilean child cohort (N = 468, 48.9% girls; 19.2% children of migrant mothers) from ages three to six, spanning the pre-, during-, and post-COVID-19 periods. Group-based multitrajectory modeling identified five profiles: three lower-symptom (82.9%) and two higher-risk groups (17.1%), characterized by persistent or escalating co-occurring internalizing and externalizing problems. Early high symptoms predicted continued -difficulties through age 6. Prepandemic negative affect and maternal depressive symptoms were early risk factors, while COVID-related stressors-hostile parenting and income loss-predicted higher-risk group membership. Maternal mental health deterioration further contributed to symptom escalation. Findings highlight the heterogeneity of early childhood mental health -postpandemic and the need for early identification of psychosocial risk factors.