Background: The plasmid mediated AmpC β-lactamases (pAmpCs) production is one of the most essential mechanism of drug resistance in Klebsiella pneumoniae (K. pneumoniae). Objective: Phenotypic and genotypic investigation of plasmid mediated AmpC β -lactamase production in K. pneumoniae and its antimicrobial profile among pediatric patients. Methodology: Ninety-two K. pneumoniae isolates were tested for pAmpC β-lactamase production by cefoxitin disk diffusion test. Multiplex polymerase chain reaction (multiplex PCR) was done to detect plasmid mediated AmpC β-lactamases genes in the cefoxitin resistant isolates. Antimicrobial susceptibility testing was done to pAmpC β- lactamase positive isolates by means of Kirby Bauer disc diffusion method. Results: Out of the 92 K. pneumoniae isolates, 37 strains (40.21%) were resistant to cefoxitin. Plasmid mediated AmpC genes were detected in 67.56% (25/37), ten isolates (40%) had CMY gene, 8 isolates (32%) had DHA gene and 7 isolates (28%) had FOX gene. All of the 25(100%) isolates were resistant to co-amoxiclav, ceftazidime, cefotaxime, cefuroxime, ceftriaxone and cefoxitin and 7 isolates (28%) showed resistance against imipenem with variable susceptibilities to the other antibiotics. Conclusion: Monitoring of Plasmid mediated AmpC β-lactamase producing K. pneumoniae is important because of its high prevalence among pediatric patients. Imipenem was the drug of choice for treatment of such infections.