A new method to predict the debonding behavior of fiber-matrix interface has been proposed by applying the principles of the micromechanics of inclusion and fracture mechanics. The validity of the mathematical model is further verified by uniaxial tension tests carried out on steel fiber reinforced cementitious composite specimens by employing a digitally controlled closed-loop MTS testing machine. It is demonstrated that the debonding occurs before the bend over point and the debonded lengths are largely influenced by the sequence of the occurrence of transverse matrix cracks and the loading stage. A stable growth of debonding has been observed in the investigation. The measured debonded lengths are compared with the theoretical prediction of the proposed model. A reasonable agreement is observed.