Background: The rising prevalence of food allergy (FA) contrasts with the inconclusive role of early-life antibiotic exposure. Given the widespread clinical application of cephalosporins in obstetrics and infancy , this represents a critical knowledge gap. This study therefore employs a prospective birth cohort design to precisely investigate the association between time-specific cephalosporin exposure and subsequent FA risk. Methods: We enrolled 1275 mother-infant pairs and prospectively monitored them for six months, recording antibiotic exposure and collecting infant fecal samples at six months of age for gut microbiota analysis. Results: 1052 dyads had completed the study , and 224 children met the diagnostic criteria for FA. Analysis of 939 eligible mother-child pairs revealed that infants with positive family allergic history (aOR = 1.621), cephalosporins exposure within 0-1 months of age (aOR=10.285) or 1-2month of age (aOR=3.094), as well as longer intervals between intrapartum cephalosporins administration and fetal delivery (aOR=1.155) faced a significantly higher risk of FA. Gut microbiota and metabolite analyses suggested cephalosporins may induce FA by disrupting the gut microbiota, which subsequently leads to metabolic disorder, especially tryptophan and NO generation pathways, ultimately resulting in intestinal barrier damage and Th2 immune imbalance. Conclusions: Our study identifies early-life cephalosporins exposure as a risk factor for FA, which most likely through restructuring gut microbiota and downstream dysregulation of antiinflammatory/ antioxidant pathways. These findings underscore the importance of precise administration of obstetric antibiotics and optimization of early-life antibiotic use. Furthermore, the identified microbiota-metabolite-FA correlations offer new avenues for managing FA progression and symptoms.