Cellulase enzyme complex is comprised of three enzymes namely exo-glucanase, endo-glucanase and β-glucosidase which act synergistically to deconstruct cellulosic biomass in order to produce fermentable sugars. The enzymes are produced naturally by the living organisms such as bacteria, fungi and algae. The majority of microorganisms that live in extreme environments including hot/cold springs, rumen stomach, deep ocean trench, acidic/alkaline pH environment, have been regarded as appealing producers of cellulase. Cellulases produced by microorganisms have enormous applications in different industries such as agriculture, food and feed production, brewing, textile, laundry and biofuel production. Scientists as well as industry researchers consider cellulases as a prospective candidate for further studies due to the intricacy of the enzyme system and massive industrial potential. Scientific belief in its production and further studies challenges are receiving greater attention these days, notably in the intent of decreasing its production cost at the industrial scale. In this review, future possibilities of using cellulase for various industrial applications are also addressed.