Neonatal sepsis is a great challenge for clinicians and infection control practitioners, especially in facilities with limited resources. Carbapenem-resistant Klebsiella pneumoniae (CRKP) is rapidly increasing and carriages a major threat to neonates. We aimed to examine phenotypes causing neonatal late onset sepsis (NLOS) in comparison with neonatal early onset sepsis (NEOS) with further investigations of genotypes, and genetic relatedness of CRKP in neonatal late-onset sepsis. Our study included 88 neonates diagnosed with sepsis: 58 with (NLOS) and 30 with (NEOS) from November 2015 to April 2016, at neonatal intensive care unit (NICU) of Cairo University Hospital. K. pneumoniae was the most common encountered pathogen in the NLOS group (37.9%) with a mean sepsis score of 6.39 when compared to the NEOS group (p < 0.05). In Klebsiella group, C-reactive protein and interleukin-6 levels were significantly high (p ˂ 0.001) and 56.5% of the isolates were meropenem resistant. The most prevalent carbapenemase gene was OXA-48 which was identified in 14/23 (60.8%) followed by NDM-1 which was identified in 12/23 (52.2%) as detected by multiplex PCR. Coexistence of both carbapenemases was found in 52.2% (12/23). The blaKPC, blaIMP, and blaVIM genes were not harbored in the isolates. By investigating the genetic relatedness of CRKP by pulsed-field gel electrophoresis, 23 isolates of K. pneumoniae revealed various pulsed-field gel electrophoresis (PFGE) patterns, demonstrating that the isolates were non-clonal. Awareness of the existing phenotypes and genotypes is important for proper treatment and infection control practices.