In this study, the physiological and biochemical response of model insect Galleria mellonella due to Klebsiella oxytoca infection was investigated. Changes in metabolic enzyme activities such as aspartate transferase (AST), alanine transferase (ALT), alkaline phosphatase (ALP), amylase (AMYL) and gamma glutamyl transferase (GGT) occurred due to K. oxytoca infection. In addition, amounts of non-enzymatic antioxidant such as uric acid (UA), bilirubin (BIL) and albumin (ALB) were altered in G. mellonella hemolymph due to infection. The results obtained from this study showed that G. mellonella can be used as a model organism in the evaluation of the physiological effects of K. oxytoca infection on the host.