This paper experimentally investigates the effects of embedded polypropylene fibers (PP fibers) on the mechanical properties- including compression strength, split tensile strength, flexural strength, fracture ductility, and fracture energy-of ultra-high-strength reactive powder concrete (RPC). A large-scale laser profilometer was employed to obtain the three-dimensional (3-D) geometry of the fracture surfaces of the prism specimens after three-point bending tests. Scanning electron microscopy was used to characterize the microstructure of the fibered RPC. Experimental results indicate that the addition of PP fibers with a volume fraction ρv less than 0.3% had insignificant effects on the mechanical strengths of RPC. The addition of PP fibers with ρv ranging between 0.3 and 0.9% improved the mechanical strengths and the fracture performances. All the measured mechanical properties of the fibered RPC decreased to a certain extent, as ρv exceeded 0.9%. The reinforcement mechanisms of the PP fibers in RPC are analyzed and discussed.