Fibers are widely used in concrete structures to control crack propagation and widening due to sustained or impact loads. Nevertheless, the concrete’s mechanical and structural properties are strongly affected by the fibers’ spatial distribution and clumping tendency within the mass material. The main objective of this paper is to assess the efficiency of stochastic finite element modeling to predict the shear strength properties of fiber-reinforced concrete (FRC) beams without stirrups, as tested by four-point loading. Polypropylene and polyvinyl alcohol micro-filament fibers are investigated in this experimental program at relatively high rates, varying from 0.5% to 1% by volume. A stochastic sensitivity analysis is performed using both random fields and random variables to determine the effect of fiber additions on the concrete’s mechanical properties (i.e., splitting tensile strength and modulus of elasticity) including the beam cracking patterns, ductility, mid-span deflection, and ultimate load. Such data could be of interest to civil engineers and structural designers to reduce the effort and resources needed to assess the FRC strength variability and failure behaviors of structural members.