The kinetics of glucose oxidation by glucose oxidase (GOx) were evaluated with mediation by two different osmium redox polymers and in the presence and absence of oxygen (O2). A one- dimensional model was designed to incorporate the effect of O2 reduction, which competes with the mediator for electrons from glucose oxidation at GOx. Kinetic parameters were determined by fitting the experimental current density measurements for varying potential, glucose and O2 concentrations. It was demonstrated that the presence of O₂ affects both the turnover number, k_cat, and Michaelis constant, K_M, of the enzyme, indicative of a mixed inhibition mechanism. Kinetic parameters specific to the mediator reaction were an order of magnitude higher than other homogeneous mediated systems, leading to high mediation efficiency. Bimolecular rate constants for GOx-oxygen reaction were found to be an order of magnitude lower than that of the free solution, which can be attributed to the reduced activity of immobilized GOx.