In this study, a simplified approach to correlate the experimental tensile strength values of the randomly oriented short fiber (SF) reinforced polymer-based composites is presented. For this purpose, a constitutive model to correlate the experimental tensile strength values of SF reinforced composites is derived. The constitutive model was derived based on a rule of mixtures. The experimental results on the Short Carbon Fiber (SCF) reinforced composites reported in our earlier works show a non-linear increase in its tensile strength as the fiber volume fraction is increased. The experimental strength of the composite was found to be significantly dependent on the interfacial stress at the fiber–matrix interface and the percentage of fibers oriented in the loading (tensile) direction. Thus, the orientation dependence of the fibers was incorporated by assuming that the percentage of aligned fibers follow the Weibull Probability Distribution Function (PDF). Additionally, the derived constitutive model was verified against the reported tensile strength data of SCF composites. The correlations of the experimental results from our earlier published work and from other available data in the literature, with the proposed model, were found to be in good agreement. The analytical model was compared to other analytical models and found that the current model showed better agreement with the reported experimental results.