In the current study, the associations of reward sensitivity with weight related behaviors and body mass index were investigated in a general population sample of 443 Flemish children (50.3% boys) aged 5.5–12 years. Cross-sectional data on palatable food consumption frequency, screen time, physical activity, parental education level and measured length and weight were collected. The Drive subscale of the ‘Behavioral Inhibition Scale/Behavioral Activation Scale’ was used as a short method to measure reward sensitivity. A significant positive association of reward sensitivity with the fast food and sweet drink consumption frequency was found. Furthermore, a significant positive association of reward sensitivity with the z-score of body mass index was demonstrated, which explained additional variance to the variance explained by palatable food consumption frequency, screen time, physical activity and parental education level. Hence, the assessment of reward sensitivity may have an added value to the assessment of weight-related behavior indicators when evaluating the determinants of overweight in a child. In sum, children high in reward sensitivity might be more attracted to fast food and sweet drinks, and hence, might be more vulnerable to develop unfavorable food habits and overweight. These findings suggest that considering inter-individual differences in reward sensitivity is of importance in future childhood obesity prevention campaigns.