This study involves the evaluation of the potential of commercial cellulase enzyme for the deinking of mixed office waste paper. The pH and temperature optima for the enzyme were 6.0 and 50°C. Enzyme dose and reaction time for the deinking process were optimized. An optimum dose of 300 g/t and reaction time of 90 min for commercial cellulase enzyme significantly improved deinking efficiency (79.3%) than the control set (59.4%) and chemical deinking (75.7%). Strength properties (except tear index) like tensile index, breaking length, burst factor and double fold were improved at optimized conditions. Cleanliness of pulp in terms of dirt and specks contents was also improved up to a significant level after cellulase treatment. Thus, it was concluded that commercial cellulase enzyme-based deinking was better than chemical deinking of mixed office waste in terms of improved pulp and paper quality.