Antimicrobial resistance (AMR) in Gram-negative bacteria poses a severe global health threat, with metabolic reprogramming emerging as a key driver of resistance development. This study integrated transcriptomic and metabolomic analyses to investigate metabolic alterations associated with cephalosporin resistance in Escherichia coli and Klebsiella pneumoniae. Results revealed upregulation of central carbon metabolism pathways, including glycolysis and the tricarboxylic acid cycle, alongside enhanced biosynthesis of branched-chain amino acids and fatty acids in resistant strains. Transcriptomic data identified overexpression of genes encoding metabolic enzymes (e.g., pyruvate kinase, isocitrate dehydrogenase) and efflux pump components, suggesting a coordinated metabolic-efflux network. Metabolomic profiling confirmed accumulation of key metabolites (e.g., pyruvate, succinate, valine) that contribute to energy production and cell wall modification. These findings highlight the critical role of metabolic regulation in AMR and provide potential targets for developing novel antimicrobial strategies.