Poultry meat can be contaminated by different types of microorganisms during processing in processing plant. The microbiological quality of chicken carcasses and along with processing steps and environmental condition was analyzed in this study in an ISO 22000:2005 certified poultry processing plant of Kathmandu. Standard plate count method was applied for the enumeration and detection of total mesophilic bacteria, total coliform, total faecal coliform, Staphylococcus load along with selected pathogens like Salmonella spp., S. aureus, Escherichia coli, Clostridium perfringens, and Listeria spp. in chicken meat at four processing step (evisceration, final washing, frozen and market). It was observed that the level of microbial load decreased with subsequent processing phases in poultry processing plant where high level of bacteria were reduced during final washing and frozen phase. After processing poultry meat in an ISO 22000:2005 certified meat processing plant, total aerobic mesophilic count, total coliform count, total faecal coliform count, total Staphylococcus count were decreased from 6.92 to 4.45 log CFU/g, 3.49 to 2.19 log CFU/g, 2.41 to nil log CFU/g, and 3..43 to 1.99 log CFU/g respectively. Pathogenic bacteria like Salmonella spp., C. perfringens, and Listeria spp. were absent in chicken meat at the fourth processing step. Prevalence of E. coli was reduced from 37.4% to 10.2%, whereas S. aureus was decreased from 18.57% to 17.1%. It was concluded that the final washing and freezing steps were the Critical Control Point (CCP) to control microbial hazards in poultry processing phase.