Various fibers have been used to reinforce concrete to enhance properties of cement. This review critically analyses the use of different natural and synthetic fibers, the treatments done on some of them to be used in concrete, their strength and weaknesses to be used for such applications. In natural fibers, bamboo coir and jute which have been extensively used have been discussed. Also, the effect of alkali present in cement mixture on the degradation of natural fibers has been detailed. Critical observations such as change in crack pattern, effect of nature of fibers, and the environment in which they are reinforced have been discussed. Effect of use of different sealing materials for the hydrophobic fibers on the ultimate property of the reinforced concrete has been reviewed for various fibers. A comprehensive review of the synthetic fibers predominantly used in such reinforcements—PP, PE, and nylon—has been given along with a critical comparative study of recent developments in the field. The fiber–matrix interface studies have been discussed and further research areas have been suggested.