A growing body of evidence has shown the association of personality with obesity, but findings of such studies in children remain mixed. This review aimed to systematically summarize the existing literature regarding the association between personality and childhood obesity and explore the underlying mechanisms. A meta-analysis was performed based on the data from 12 included studies and personality traits were classified into five domains (Extraversion, Agreeableness, Conscientiousness, Neuroticism, and Openness) based on the five-factor model. Conscientiousness was significantly associated with BMI across 2 studies and the pooled correlation coefficient was -0.09 (95% CI: -0.17 to 0.00; I2 = 0%); another 3 studies indicated a significant difference in Conscientiousness between children with obesity and those with normal weight, and the pooled SMD was -0.08 (95% CI: -0.13 to -0.03; I2 = 66%). No consistent patterns were found in the associations between other personality traits and childhood obesity. We hypothesized three possible pathways (moderation, mediation, and confounding) underlying the personality-obesity associations. Findings of our review indicate that, within the context of childhood obesity interventions, identification of subgroups of children with specific personality traits is necessary, especially for measures of Conscientiousness.