Childhood asthma and obesity are rising in prevalence, and obesity-related asthma has emerged as a distinct clinical phenotype. In children, obesity is not only a trigger for asthma but also a key pathophysiological driver of disease progression and a modifier of treatment response. In obesity, shifts in the composition of the gut microbiota and its metabolites can activate pulmonary immunity through the gut-lung axis, while obesity-induced chronic systemic inflammation and metabolic dysregulation are closely linked to pulmonary immune imbalance, airway remodeling, and airway hyperresponsiveness. Together, these processes constitute the microbiota-immune-metabolism axis. This review summarizes potential mechanisms by which obesity influences childhood asthma via this axis and aims to deepen mechanistic understanding and provide research directions and targets for clinical intervention and translation.