Background: Carbapenem-resistant clinical isolates are extending rapidly, and in past recent years, carbapenem resistance has become an important health problem worldwide. This study aimed to investigate the carbapenem-resistance genes in extended-spectrum β-lactamase (ESBL) producing K. pneumoniae isolates. Methods: Seventy-five non-duplicate clinical K. pneumoniae strains were isolated from urine, blood, sputum, and wound samples. Antimicrobial susceptibility tests for 12 different antibiotics were performed using the disk diffusion method, followed by the determination of minimum inhibitory concentrations (MIC) of imipenem and meropenem. Phenotypic detection of ESBL and carbapenemase enzymes was performed by disk Disc Diffusion Synergy test (DDST) and modified Hodge test (MHT), respectively. Resistant isolates were further investigated for ESBL and carbapenemase genes by the PCR assay. Results: The highest and lowest resistance rates were observed against ampicillin (93.3%) and tigecycline (9.3%), respectively. Based on the results of phenotypic tests, 46.7% and 25.3% were positive for ESBL and carbapenemase enzymes, respectively. In addition, using the molecular method, the predominant ESBL-, and carbapenemase-associated genes were blaTEM (34.3%) and blaOXA-48 (57.8%), respectively. Conclusion: Based on the study, it has been found that K. pneumoniae strains produce significant rates of beta-lactamase enzymes, which is extremely alarming. As carbapenem resistance is an alarming public health issue, early detection of the isolates and effective infection control measures are necessary to prevent their further spreading.