The association between stress in early life and obesity and overweight in adulthood is well established. There is also increasing evidence of a link between stress exposure in childhood (or in utero) and child and adolescent obesity. Major sources of early life stress include adverse childhood experiences (e.g., abuse), poverty, food insecurity, and poor relationships with primary caregivers. Exposure to chronic and acute early life stressors can disrupt the biological stress regulation system, change the structure of regions of the brain responsible for emotion regulation and other important tasks, and promote eating behaviors and dietary patterns, as well as lifestyle factors (e.g., poor sleep, low physical activity), that may increase obesity risk. This research review summarizes and provides examples from the scientific literature on the association between early life stress exposure and childhood obesity risk. The review finds that there are multiple, highly intertwined biological, behavioral, and cross-cutting pathways that are altered by acute and chronic stress exposure in ways that contribute to heightened obesity risk. Developing a better understanding of the mechanisms that link early life stress exposures with childhood obesity risk will be particularly important for developing future childhood obesity prevention interventions that seek to reduce health disparities.